Exception when handling multiple hostnames in Composite C1 - asp.net

I have a problem configuring multiple hostnames in Composite C1.
Background:
I have two websites in C1: site1 and site2. The C1 installation is mainly for site1 and works with the host www.site1.com (and alias site1.com).
Now I've added another site, site2, to C1. When browsing to site1.com/site2 I end up on the site2 website. All fine. Then I try to add another hostname, www.site2.com, to URL Configuration -> Hostnames. After adding www.site2.com and browsing to www.site2.com I get the following exception: "Item has already been added. Key in dictionary: '' Key being added: ''"
The stacktrace looks as follows:
[ArgumentException: Item has already been added. Key in dictionary: '' Key being added: '']
System.Collections.Hashtable.Insert(Object key, Object nvalue, Boolean add) +9353115
System.Collections.Hashtable.Add(Object key, Object value) +11
Composite.Core.Collections.Generic.Hashtable`2.Add(TKey key, TValue value) +105
Composite.Plugins.Routing.Pages.PageUrlBuilder.BuildUrlSet(IPage page, Guid parentPageId) +1935
Composite.Core.WebClient.Renderings.Page.PageStructureInfo.BuildFolderPaths(SitemapBuildingData pagesData, IEnumerable`1 elements, IDictionary`2 urlToIdLookup, IPageUrlBuilder builder) +253
Composite.Core.WebClient.Renderings.Page.PageStructureInfo.BuildMap(UrlSpace urlSpace) +2200
Composite.Core.WebClient.Renderings.Page.PageStructureInfo.GetMap(PublicationScope publicationScope, CultureInfo localizationScope, UrlSpace urlSpace) +482
Composite.Core.WebClient.Renderings.Page.PageStructureInfo.GetPageUrlBuilder(PublicationScope publicationScope, CultureInfo localizationScope, UrlSpace urlSpace) +9
Composite.Plugins.Routing.Pages.DefaultPageUrlProvider.ParseUrl(String relativeUrl, UrlSpace urlSpace, UrlKind& urlKind) +311 Composite.Plugins.Routing.Pages.DefaultPageUrlProvider.ParseUrl(String absoluteUrl, UrlKind& urlKind) +306 Composite.Core.Routing.Pages.C1PageRoute.GetRouteData(HttpContextBase context) +156
System.Web.Routing.RouteCollection.GetRouteData(HttpContextBase httpContext) +287
System.Web.Routing.UrlRoutingModule.PostResolveRequestCache(HttpContextBase context) +60
System.Web.Routing.UrlRoutingModule.OnApplicationPostResolveRequestCache(Object sender, EventArgs e) +86
System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +148
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75
Does anyone have a solution for this?
Thanks in advance...
UPDATE:
After changing the dll suggested by Dmitry Dzygin I get the following stack trace:
[ArgumentException: Item has already been added. Key in dictionary: '' Key being added: '']
System.Collections.Hashtable.Insert(Object key, Object nvalue, Boolean add) +9353115
System.Collections.Hashtable.Add(Object key, Object value) +11
Composite.Core.Collections.Generic.Hashtable`2.Add(TKey key, TValue value) in c:\Builds\1\Freja\CodeplexBuild\Sources\Public\Composite\Core\Collections\Generic\Hashtable.cs:28
Composite.Plugins.Routing.Pages.PageUrlBuilder.BuildUrlSet(IPage page, Guid parentPageId) in c:\Builds\1\Freja\CodeplexBuild\Sources\Public\Composite\Plugins\Routing\Pages\PageUrlBuilder.cs:190
Composite.Core.WebClient.Renderings.Page.PageStructureInfo.BuildFolderPaths(SitemapBuildingData pagesData, IEnumerable`1 elements, IDictionary`2 urlToIdLookup, IPageUrlBuilder builder) in c:\Builds\1\Freja\CodeplexBuild\Sources\Public\Composite\Core\WebClient\Renderings\Page\PageStructureInfo.cs:630
Composite.Core.WebClient.Renderings.Page.PageStructureInfo.BuildFolderPaths(SitemapBuildingData pagesData, IEnumerable`1 roots, IPageUrlBuilder pageUrlBuilder, IDictionary`2 urlToIdLookup) in c:\Builds\1\Freja\CodeplexBuild\Sources\Public\Composite\Core\WebClient\Renderings\Page\PageStructureInfo.cs:612
Composite.Core.WebClient.Renderings.Page.PageStructureInfo.BuildMap(UrlSpace urlSpace) in c:\Builds\1\Freja\CodeplexBuild\Sources\Public\Composite\Core\WebClient\Renderings\Page\PageStructureInfo.cs:559
Composite.Core.WebClient.Renderings.Page.PageStructureInfo.GetMap(PublicationScope publicationScope, CultureInfo localizationScope, UrlSpace urlSpace) in c:\Builds\1\Freja\CodeplexBuild\Sources\Public\Composite\Core\WebClient\Renderings\Page\PageStructureInfo.cs:277
Composite.Core.WebClient.Renderings.Page.PageStructureInfo.GetPageUrlBuilder(PublicationScope publicationScope, CultureInfo localizationScope, UrlSpace urlSpace) in c:\Builds\1\Freja\CodeplexBuild\Sources\Public\Composite\Core\WebClient\Renderings\Page\PageStructureInfo.cs:342
Composite.Plugins.Routing.Pages.DefaultPageUrlProvider.ParseUrl(String relativeUrl, UrlSpace urlSpace, UrlKind& urlKind) in c:\Builds\1\Freja\CodeplexBuild\Sources\Public\Composite\Plugins\Routing\Pages\DefaultPageUrlProvider.cs:249
Composite.Plugins.Routing.Pages.DefaultPageUrlProvider.ParseUrl(String absoluteUrl, UrlKind& urlKind) in c:\Builds\1\Freja\CodeplexBuild\Sources\Public\Composite\Plugins\Routing\Pages\DefaultPageUrlProvider.cs:206
Composite.Core.Routing.Pages.C1PageRoute.GetRouteData(HttpContextBase context) in c:\Builds\1\Freja\CodeplexBuild\Sources\Public\Composite\Core\Routing\Pages\C1PageRoute.cs:90
System.Web.Routing.RouteCollection.GetRouteData(HttpContextBase httpContext) +287
System.Web.Routing.UrlRoutingModule.PostResolveRequestCache(HttpContextBase context) +60
System.Web.Routing.UrlRoutingModule.OnApplicationPostResolveRequestCache(Object sender, EventArgs e) +86
System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +148
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75

Looks like some of kind of a url collision when 2 C1 pages received the same url or something like that. As a solution I recommend you to copy debug version Composite.dll file and Composite.pdf files to the /bin folder of your website. You can find those at Codeplex in "Other available downloads section" of the release page ( http://compositec1.codeplex.com/releases/view/80764 ) After that you will see the exact line in the code that caused it. Once you have it, I'll be able to either fix it or to add some code assertions/validation logic.
Update.
Looking through code it appears that the exception is possible only if you have 2 websites with empty "UrlTitle" field. Normally there's validation logic that prevents this situation from happenning. Try to edit both website's roots, give them not empty "Url Title" fields, and publish them afterwards, that should solve the issue. If the bug is still persists, I either need a better repro (I failed to reproduce it with the provided one), or if you send me a copy of a website, I'll debug it.

Related

Caching LINQ-SQL objects and DataContext thread safety

We are querying database using LINQ-SQL and then storing resulting master table objects in HTTP cache.
Later, the master objects are being used to query its children, using lazy loading. Here are the relevant pieces of code - I have recreated the scenario in a new proof-of-concept app:
if (HttpRuntime.Cache["c"] == null)
{
LockApp.Models.DBDataContext db = new Models.DBDataContext();
var master = db.Masters.ToList();
HttpRuntime.Cache.Add("c", master,
null, DateTime.Now.AddMonths(1),
TimeSpan.Zero, CacheItemPriority.Normal, null);
}
ViewBag.Data = (List<LockApp.Models.Master>)HttpRuntime.Cache["c"];
And here's the razor view that is iterating over master and detail objects:
#foreach(var m in ViewBag.Data){
#m.Id<nbsp></nbsp>
foreach(var d in m.Details){
#d.Id<nbsp></nbsp>
}
<br />
}
It works perfectly fine and caches the data correctly. However, it fails when there are multiple requests trying to hit the web site after cache is cleared - I am testing this using JMeter, basically hitting the site with many (50) parallel threads, and then touching web.config - I immediately start seeing one of the following two errors:
Index was outside the bounds of the array
at foreach(var d in m.Details)
this error never goes away, i.e. some data gets corrupted in cache
with following stack:
System.Collections.Generic.List`1.Add(T item) +34
System.Data.Linq.SqlClient.SqlConnectionManager.UseConnection(IConnectionUser user) +305
System.Data.Linq.SqlClient.SqlProvider.Execute(Expression query, QueryInfo queryInfo, IObjectReaderFactory factory, Object[] parentArgs, Object[] userArgs, ICompiledSubQuery[] subQueries, Object lastResult) +59
System.Data.Linq.SqlClient.SqlProvider.ExecuteAll(Expression query, QueryInfo[] queryInfos, IObjectReaderFactory factory, Object[] userArguments, ICompiledSubQuery[] subQueries) +118
System.Data.Linq.SqlClient.CompiledQuery.Execute(IProvider provider, Object[] arguments) +99
System.Data.Linq.DeferredSourceFactory`1.ExecuteKeyQuery(Object[] keyValues) +402
System.Data.Linq.DeferredSourceFactory`1.Execute(Object instance) +888
System.Data.Linq.DeferredSource.GetEnumerator() +51
System.Data.Linq.EntitySet`1.Load() +107
System.Data.Linq.EntitySet`1.GetEnumerator() +13
System.Data.Linq.EntitySet`1.System.Collections.IEnumerable.GetEnumerator() +4
ASP._Page_Views_Home_Index_cshtml.Execute() in c:\Users\prc0092\Documents\Visual Studio 2012\Projects\LockApp\LockApp\Views\Home\Index.cshtml:16
or this error
ExecuteReader requires an open and available Connection. The connection's current state is open.
at the same line foreach(var d in m.Details)
this error does go away after a while if I stop hitting the site with parallel requests
with following stack
System.Data.SqlClient.SqlConnection.GetOpenConnection(String method) +5316460
System.Data.SqlClient.SqlConnection.ValidateConnectionForExecute(String method, SqlCommand command) +7
System.Data.SqlClient.SqlCommand.ValidateCommand(String method, Boolean async) +155
System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean asyncWrite) +82
System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) +53
System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method) +134
System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior) +41
System.Data.Common.DbCommand.ExecuteReader() +12
System.Data.Linq.SqlClient.SqlProvider.Execute(Expression query, QueryInfo queryInfo, IObjectReaderFactory factory, Object[] parentArgs, Object[] userArgs, ICompiledSubQuery[] subQueries, Object lastResult) +1306
System.Data.Linq.SqlClient.SqlProvider.ExecuteAll(Expression query, QueryInfo[] queryInfos, IObjectReaderFactory factory, Object[] userArguments, ICompiledSubQuery[] subQueries) +118
System.Data.Linq.SqlClient.CompiledQuery.Execute(IProvider provider, Object[] arguments) +99
System.Data.Linq.DeferredSourceFactory`1.ExecuteKeyQuery(Object[] keyValues) +402
System.Data.Linq.DeferredSourceFactory`1.Execute(Object instance) +888
System.Data.Linq.DeferredSource.GetEnumerator() +51
System.Data.Linq.EntitySet`1.Load() +107
System.Data.Linq.EntitySet`1.GetEnumerator() +13
System.Data.Linq.EntitySet`1.System.Collections.IEnumerable.GetEnumerator() +4
ASP._Page_Views_Home_Index_cshtml.Execute() in c:\Users\prc0092\Documents\Visual Studio 2012\Projects\LockApp\LockApp\Views\Home\Index.cshtml:16
Different things I tried
Double locking
Doesn't help
private static object ThisLock = new object();
public ActionResult Index()
{
if (HttpRuntime.Cache["c"] == null)
{
lock (ThisLock)
{
if (HttpRuntime.Cache["c"] == null)
{
Loading child data upfront
Works, but requires constant maintenance as not all children should be loaded upfront, plus see next note
DataLoadOptions dlo = new DataLoadOptions();
dlo.LoadWith<Master>(b => b.Details);
db.LoadOptions = dlo;
Locking the master object while trying to access its children
Again, requires maintenance as all initial places where child is accessed need to be found - we are struggling with this as there are different entry paths into the site
#foreach(var m in ViewBag.Data){
#m.Id<nbsp></nbsp>
lock (m){
foreach(var d in m.Details){
#d.Id<nbsp></nbsp>
}
}
<br />
}
Switching to entity framework
This seems to still have (sometimes - much better than linq-sql) the "open connection" issue at certain number of parallel requests (50+ on core i7) - it does go away after a while as I mentioned and I haven't seen data corruption yet.
We may end up switching to EF completely as this seems to be the only viable path - assuming data corruption doesn't show up - that is to be tested on my actual project.
I am not optimistic though, as EF data context is not thread safe either, and I think the EF data objects carry their context with them. This is probably the only question that I don't have answer to yet.
Theories on why it's broken
It looks like storing LINQ-SQL object in http cache carries the data context with it. When this context is later used by multiple threads to access children, there is some type of concurrency issue that manifests itself in either temporary connectivity issue or complete data corruption of the child object. As there's no way to disconnect/reconnect the context from the LINQ object, it looks like the only suggestion is not to cache LINQ objects that need lazy-loading of their children - a substantial number of google searches I did does not seem to give you that advice, in fact sometimes it's opposite.
I have uploaded the complete project (for Visual Studio 2012 and SQL Server 2012)
https://docs.google.com/file/d/0B8CQRA9dD8POb3U5RGtCV3BMeU0/edit?usp=sharing
and a simple JMeter script that will hit your local machine with parallel requests:
https://docs.google.com/file/d/0B8CQRA9dD8POd1VYdGRDMEFQbEU/edit?usp=sharing
to test, start the site and run the test - then touch the web.config on the site
LockApp.Models.DBDataContext db = new Models.DBDataContext();
var master = db.Masters.ToList();
You should have a call to db.ObjectTrackingEnabled = false in between these two calls. Otherwise all of the objects will be tracked by the datacontext so that changes can be written back into the database. Since you're caching these objects to be read by multiple threads, you do not want this. (It's also more expensive even in single-threaded cases to track objects you won't change, so worth doing in other places).
Also, use LoadWith to eagerly load any properties you might want to access of these cached entities, so they are all loaded on the initial caching thread, rather than with (potentially mulitple) threads that try to access them.

All MVC pages fail with the message an item with the same key has already been added

Ultimately I am trying to address the same issue that is referenced in Loading any MVC page fails with the error “An item with the same key has already been added.” and An item with the same key has already been added. A duplicate of the first link is All MVC pages fail with the message an item with the same key has already been added but it has some additional pertinent information, confirming that it only effects MVC pages, while webforms and other aspects of the application that deal with appSettings continue to work without error.
I have now seen this four times in production and it has not been seen in any other environment (dev, test, UAT). I have closely examined and debugged through the source code of System.Web.WebPages and the relevant sections of the MVC stack but did not run into anything that stood out. This problem has persisted through a migration from MVC3 to MVC4, and the latest changeset from aspnetwebstack.codeplex.com does not appear to address this issue.
A quick summary of the issue:
Every MVC page is affected and completely unusable
WebForms and other aspects of the application that use appSettings continue to work just fine
Only an appPool restart will correct this issue
At least once and as referenced in an article above, this has happened after a regular time interval recycle of the appPool by IIS
This has happened during both low and high volume traffic periods
This has happened on multiple production servers, but the issue only affects a single server at any given time, as other servers continue serving MVC pages
The offending line of code is var items = new Lazy<Dictionary<object, object>>(() => appSettings.AllKeys.ToDictionary(key => key, key => (object)appSettings[key], comparer));, but it occurs when the lazy initialization is forced by requesting a value from items The appSettings variable is from System.Web.WebConfigurationManager.AppSettings which is a direct static reference to System.Configuration.ConfigurationManager.AppSettings. So I beleive the line is equivalent to: var items = new Lazy<Dictionary<object, object>>(() => System.Configuration.ConfigurationManager.AppSettings.AllKeys.ToDictionary(key => key, key => (object)appSettings[key], comparer));
I rarely suspect framework issues, but it appears that appSettings has two distinct keys that are the same (not the same as a NameValueCollection supporting multiple values for the same key). The comparer being used in the MVC stack is the StringComparer.OrdinalIgnoreCase which appears to match what is used by the configuration system. If this is a framework issue, the MVC stack appears to be very unforgiving when it forces the NameValueColleciton into a dictionary using the ToDictionary() extension method. I believe using appSettings.AllKeys.Distinct().ToDictionary(...) would probably allow the MVC stack to operate normally as the rest of the application does and be oblivious to the possibility of duplicate keys. This unforgiving nature appears to also contribute to the issue described in NullReferenceException in WebConfigScopeDictionary
Server stack trace:
at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
at System.Web.WebPages.Scope.WebConfigScopeDictionary.<>c__DisplayClass4.<.ctor>b__0()
at System.Lazy`1.CreateValue()
Exception rethrown at [0]:
at System.Lazy`1.get_Value()
at System.Web.WebPages.Scope.WebConfigScopeDictionary.TryGetValue(Object key, Object& value)
at System.Web.Mvc.ViewContext.ScopeGet[TValue](IDictionary`2 scope, String name, TValue defaultValue)
at System.Web.Mvc.ViewContext.ScopeCache..ctor(IDictionary`2 scope)
at System.Web.Mvc.ViewContext.ScopeCache.Get(IDictionary`2 scope, HttpContextBase httpContext)
at System.Web.Mvc.ViewContext.GetClientValidationEnabled(IDictionary`2 scope, HttpContextBase httpContext)
at System.Web.Mvc.Html.FormExtensions.FormHelper(HtmlHelper htmlHelper, String formAction, FormMethod method, IDictionary`2 htmlAttributes)
at ASP._Page_Areas_Client_Views_Equipment_Index_cshtml.Execute()
at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context)
at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1a.<InvokeActionResultWithFilters>b__17()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult)
at System.Web.Mvc.Controller.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar)
at System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar)
at System.Web.Mvc.MvcHandler.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
To separate my question from the questions already asked, I will ask has anyone seen the configuration system be corrupted with multiple duplicate keys or where a NameValueCollection.AllKeys returns two identical keys? I know you can have multiple keys defined in the config file, but the last key wins, and that scenario does not reproduce this issue.
Although I am not alone in seeing this behavior multiple times, there are relatively few posts describing this issue, so I also suspect that it might be a configuration/environmental issue, but again, servers will run for months without experiencing this issue, and an appPool restart immediately corrects the problem.
I have mitigated this issue by forcing an appPool restart if a server starts seeing this error, but management is not happy about this "hacky" solution because some user will still experience an error.
Help?!?!?
EDIT:
Here is a contrived, cheezy test that can reproduce the scenario, but doesn't help in solving the issue. It happens during approx. 20% of the test runs. The code will blow up for other threading reasons, but it is the "Same key has already been added" error that is of interest.
[TestClass]
public class UnitTest1
{
readonly NameValueCollection _nameValueCollection = new NameValueCollection();
private Lazy<Dictionary<object, object>> _items;
[TestMethod]
public void ReproduceSameKeyHasAlreadyBeenAdded()
{
Thread[] threads = new Thread[1000];
for (int i = 0; i < 1000; i++)
{
ThreadStart threadStart = AddEntry;
Thread thread = new Thread(threadStart);
threads[i] = thread;
}
foreach (var thread in threads)
thread.Start();
Thread.Sleep(100);
_items = new Lazy<Dictionary<object, object>>(() => _nameValueCollection.AllKeys.ToDictionary(key => key, key => (object)_nameValueCollection[key], ScopeStorageComparer.Instance));
object value;
_items.Value.TryGetValue("4", out value); // approx. 20% of time, blows up here with mentioned error
Assert.IsTrue(value != null);
}
private int _counter;
private void AddEntry()
{
_counter++;
try
{ // add a bunch of even keys, every other one a duplicate
_nameValueCollection.Add((_counter%2) == 0 ? _counter.ToString() : (_counter + 1).ToString(), "some value");
}
catch {}
}
}
StackTrace:
at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
at UnitTestProject1.ReproduceSameKeyHasAlreadyBeenAdded.<TestMethod1>b__0() in c:\Git\AspNetWebStack\aspnetwebstack\UnitTestProject1\UnitTest1.cs:line 37
at System.Lazy`1.CreateValue()
We came across this same issue and finally tracked it down to dynamic updating of the ConfigurationManager.AppSettings collection. I have posted a full answer here: https://stackoverflow.com/a/17415830/2423407
Are you absolutely positive the error is occurring on the line where you are initializing items and not the line on which items is being used to add to some other dictionary (Static I would presume).
To me the most likely way this would occur is if the code was executed in parallel (by two concurrent users) and the second one executing causing the exception.
As a general workaround I usually initialize a strongly typed class with all configuration parameters as an auto-start provider (and add some strongly-typed type checking of the values as well, such as checking that an int is an int, etc) to avoid run-time errors.
This has the double benefit of loading these at warmup, not when the users want the info (better response performance) and thread-safety is supposedly guaranteed with them as well.
See if that doesn't fix your issue. If you do not want to do that I would at the very least try to execute the code that is failing for you with multiple threats hitting it, as my guess would be that you will see your error occur fairly reliably.

Buffer cannot be null. Parameter name: buffer

I have written code to send an email with a link to a URL, which the user has to click for confirmation.
Sample Link:
http://localhost:3531/VerificationModule/VerifyEmail.aspx?TemplateID=519457608&F960866879F669E=Tw5NpFeW9HsAqc_Ap5dmOwqkZ041pFQGYLxRV-puumtHsfhrTYtDe51uCbGV44Kc1X3n6cggsynfqRmh74ie535ymkvATeK5Jii11tOMIZDZ_GVB8QolLeMU5i6KWEZculKhM0IOhYFaMc-DsB
But when the user clicks the link, it gets opened in the browser, but displays the following error.
"Buffer cannot be null. Parameter name: buffer"
Please find below the stack trace:
[ArgumentNullException: Buffer cannot be null.
Parameter name: buffer]
System.IO.MemoryStream..ctor(Byte[] buffer, Boolean writable) +9629927
System.IO.MemoryStream..ctor(Byte[] buffer) +6
Auth.IdentityTokenXChangeData.Deserialize(String base64Package) +187
Auth.IdentityTokenXChange.TrySniffIdentityToken(HttpRequest req, String& sessionId, String& sessionTag, String& returnUrl) +244
Auth.IdentityModule.OnBeginRequest(Object sender, EventArgs e) +365
System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +220
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +120`
This is eating up my day. Any suggestion would be of great help.
Got a clue on the error..
I believe the problem is with Encoded value in the QueryString
("F960866879F669E=Tw5NpFeW9HsAqc_Ap5dmOwqkZ041pFQGYLxRV-puumtHsfhrTYtDe51uCbGV44Kc1X3n6cggsynfqRmh74ie535ymkvATeK5Jii11tOMIZDZ_GVB8QolLe‌​MU5i6KWEZculKhM0IOhYFaMc-DsB") -
The Base64 Decode is returning 'null' for some reasons.
Method -
'System.Web.HttpServerUtility.UrlTokenDecode
("F960866879F669E=Tw5NpFeW9HsAqc_Ap5dmOwqkZ041pFQGYLxRV-puumtHsfhrTYtDe51uCbGV44Kc1X3n6cggsynfqRmh74ie535ymkvATeK5Jii11tOMIZDZ_GVB8QolLe‌​MU5i6KWEZculKhM0IOhYFaMc-DsB")'
Any idea on why it returns null? Is it not a valid Base64 encode?
It means the Auth.IdentityTokenXChangeData.Deserialize method creates a new MemoryStream instance with a null buffer argument.
This method seems specific to your code / environment (there is an Auth.IdentityModule in your site), so you need to take a look at it.

null reference exception stack

Can any one explain this exception?
Server Error in '/eims_web' Application:
Object reference not set to an instance of an object.
Description:
An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details:
System.NullReferenceException: Object reference not set to an instance of an object.
Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
Stack Trace:
[NullReferenceException: Object reference not set to an instance of an object.]
System.Xml.XmlLoader.Load(XmlDocument doc, XmlReader reader, Boolean preserveWhitespace) +24
System.Xml.XmlDocument.Load(XmlReader reader) +108
System.Web.UI.WebControls.XmlDataSource.PopulateXmlDocument(XmlDocument document, CacheDependency& dataCacheDependency, CacheDependency& transformCacheDependency) +342
System.Web.UI.WebControls.XmlDataSource.GetXmlDocument() +253
System.Web.UI.WebControls.XmlHierarchicalDataSourceView.Select() +51
System.Web.UI.WebControls.Menu.DataBindItem(MenuItem item) +326
System.Web.UI.WebControls.Menu.PerformDataBinding() +99
System.Web.UI.WebControls.HierarchicalDataBoundControl.PerformSelect() +126
System.Web.UI.WebControls.BaseDataBoundControl.DataBind() +125
System.Web.UI.WebControls.Menu.DataBind() +29
System.Web.UI.WebControls.BaseDataBoundControl.EnsureDataBound() +104
System.Web.UI.WebControls.Menu.EnsureDataBound() +70
System.Web.UI.WebControls.BaseDataBoundControl.OnPreRender(EventArgs e) +43
System.Web.UI.WebControls.Menu.OnPreRender(EventArgs e, Boolean registerScript) +89
System.Web.UI.WebControls.Menu.OnPreRender(EventArgs e) +63
System.Web.UI.Control.PreRenderRecursiveInternal() +200
System.Web.UI.Control.PreRenderRecursiveInternal() +322
System.Web.UI.Control.PreRenderRecursiveInternal() +322
System.Web.UI.Control.PreRenderRecursiveInternal() +322
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +4837
Without seeing your code it is going to be hard to say, but by the looks of the stack trace, I will wager a guess and say you have a TreeView/Menu bound to an XmlDataSource.
Clearly something is going wrong during the databinding process, but again without seeing your code that populates the XmlDataSource it is going to be next to impossible to assist you further.
The XmlReader instance passed from XmlDocument.Load to XmlLoader.Load is null, which means that XmlDataSource.PopulateXmlDocument passes a null reader to XmlDocument.Load, which occurs when XmlDataSource.GetReader returns null.
The only code path where this happens requires that XmlDataSource.DataFile is null or empty and XmlDataSource.Data is either null, empty or costs of only white-space characters.

asp.net web admin tool custom database

I am stuck into a problem here and need a hint from someone.
I am using my own SQL Server database for managing users and roles (as opposed to aspnet DB). It was working fine until I added some custom fields to the aspnet_membership table. After doing so, I cannot create a new user through the asp.net web administration tool. The following exception is thrown:
An error was encountered. Please return to the previous page and try again.
The following message may help in diagnosing the problem: Exception has been thrown by the target of an invocation. at System.RuntimeMethodHandle._InvokeMethodFast(Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner) at System.RuntimeMethodHandle.InvokeMethodFast(Object target, Object[] arguments, Signature sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner) at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks) at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) at System.Web.Administration.WebAdminMembershipProvider.CallWebAdminMembershipProviderHelperMethodOutParams(String methodName, Object[] parameters, Type[] paramTypes) at System.Web.Administration.WebAdminMembershipProvider.CreateUser(String username, String password, String email, String passwordQuestion, String passwordAnswer, Boolean isApproved, Object providerUserKey, MembershipCreateStatus& status) at System.Web.UI.WebControls.CreateUserWizard.AttemptCreateUser() at System.Web.UI.WebControls.CreateUserWizard.OnNextButtonClick(WizardNavigationEventArgs e) at System.Web.UI.WebControls.Wizard.OnBubbleEvent(Object source, EventArgs e) at System.Web.UI.WebControls.CreateUserWizard.OnBubbleEvent(Object source, EventArgs e) at System.Web.UI.WebControls.Wizard.WizardChildTable.OnBubbleEvent(Object source, EventArgs args) at System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) at System.Web.UI.WebControls.Button.OnCommand(CommandEventArgs e) at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) at System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
This occurs only at the time of user creation. Everything else is working fine. I have already tried running the aspnet_regsql utility again. Any other suggestions? Any help will be most appreciated.
--
Ali
At a guess, are any of the fields you have added defined as Not NULL and have no defaults?
If so, make sure you populate them in the code that addes a user.
Are the extra columns allowed to hold null values? Have you defined suitable default values if they aren't?
Did you update the Stored Procedures that write to the membership tables? If so, then you'll need to write a custom membership provider to populate them - what sort of details are they?
It would probably be better to store these values against a Profile for the user - unless they are explicitly to do with their membership, in which a custom provider is the way to go.
Edit to respond to Ali's comments
In that instance (marking an account as deleted/inactive) then yes, it probably makes sense to store that against the membership table - they are to do with the users membership of the site.
However - the main issue I can see with your approach is that if you're using the default Login controls, the user can still log in initially, and then you'd need to be checking the value of the Deleted field in either the LoggingIn (before Authentication) or LoggedIn (after) event handlers - you might be able to get away with modifying the built in IsApproved property to handle this by default.
Thanks Zhaph and Oded. The NULL values were problem.
But Zhaph pointed out towards another issue I would like to know more. The additional details are like isDeleted, where I just mark isDeleted as true without actually having to delete the user and then some relevant details for audit like deletedByUser, dateDeleted etc. (and some application specific).
I did not update the stored procedures that write to the membership tables. Instead, I have some additional SPs which fill in the extra details as soon as the user is created. Is that(storing field in membership table and writing new procedures) a correct way to approach?

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