What's the best way to systematically debug the aspx pages ( not C# or Vb.NET managed code). Sometimes a small syntax or semantic error in aspx page displays:
Internal server error or something similar
and I had to comment the last changes step by step to find out the error.
Is there any other systematic way of doing this?
This post might help (however you should remember to switch the application into Release mode before launching it on the production environment).
Related
I have a VS 2022 solution with a WPF client and ASP.NET backend and when I put breakpoints in the backend web services they have the yellow tag with a message:
Breakpoint will not currently be hit. No symbols have been loaded for
this document.
I run the solution with the WPF project set as the start project, but, if I test this by setting the web project as the start project - the symbols will load, but of-course this is useless as the wpf app is not running.
A little history: This solution was running on my old dev PC (same version of everything) and all worked as expected, but when loading all solutions onto my new PC, this problem started up. I have googled this and found a ton of posts about it and have tried everything, but nothing has worked yet.
I can run the solution and attach to the process and then debug, but since I will be debugging 100s and 100s of times, those extra steps are a real pain and I have been able to debug asp.net projects from wpf for many years up to now.
Can someone please recommend some additional steps I can take to solve this problem?
FYI, I Have been through everything from this link:
How do I remedy "The breakpoint will not currently be hit. No symbols have been loaded for this document." warning?
Thanks.
Common method:
In VS, go to Tools --> Options --> Debugging --> General, and then cancel the checks in front of [Enable "Only My Code"] and [Require source files to exactly match the original version].
But this method you may have tried.
Ultimate method:
When the breakpoints clicked by the mouse are invalid, you can perform the following operations in vs:
Debug --> delete all breakpoints
Debug --> New Breakpoint --> Function Breakpoint, and then enter the name of the function to add a breakpoint
I am trying to run one of the sample programs given by EditableGrid to run on my localhost with asp.net. It is that of loading json data example. It throws an exception saying:
GET http://localhost:60218/grid.json?22895 404 (Not Found)
This is the line where it occurs:
editableGrid.loadJSON("grid.json");
The JSON file is placed in my solution hierarchy as well..I am new to editablegrids, so have no clue what is going wrong here?? I also do not happen to find any or no help on editablegrids, should I be using this for grids? Or should I be looking into other plugins? Other that JQGrid...More or less similar to editablegrid..
I think the reason is very clear - the EditableGrid is run under php !
If you wish to mix php with asp.net you may try it, but is not work for the small web server that visual studio use for test and debug.
I am sorry if this is not really a coding question (it depends on if its my code causing the problem I suppose).
I have seen this question: Tracking down intermittent 'Object reference not set to an instance of an object.' error on build
However, it has not been of much help (although if you read the comments, you will see that I thought it did help for a while there).
When I try publish my website, occasionally, I will get an error with no file or line reference:
Pre-compiling Web Site
Building directory '/App_Code/'.
Building directory '/'.: Publication (web): Object reference not set to an instance of an object.
Pre-compilation Complete
------ Skipped Publish: Project X:\, Configuration: Debug Any CPU ------
I know the usual causes of "Object reference not set to an instance of an object" but this seems a bit different, isn't it supposed to be a runtime error? Not a build error?
What is weird is that it happens, seemingly at random (about 25%-33% of the time). I can try to publish it and have it fail. Then try again straight after, without changing anything and it works fine.
I started getting this error after moving some of my functions (VB.net btw) to a new file in the App_Code folder so they can be accessed by all pages of the site.
If you need any more info, please let me know.
Thanks,
EDIT: After further investigation, it seems to only happen if I try to publish the website within a few seconds of saving changes to any file within it. What could cause this?
The same error occurred for me to, I deleted the dlls of the custom controls in the web site that are already in the bin, then i published the web site, and succeeded
IF you have any custom/usercontrols in your project, they are actually running at design time and can give object ref errors. This can occur during builds too. In that case, a property is being referenced that is NOTHING and throws the error.
I had a similar problem with a Windows Form project.
Wherever I try to move a custom control on the windows form, and then try to save the form, VS2010 comes back with "Object not set to an instance of an object".
I suspected the error was deep down in the layers of abstraction in my inherited code, but couldn't work out how deep to go, without reviewing every line of code.
My solution to this problem is this.
Open up another instance of Visual Studio 2010
Menu: Debug | Attach to Process..
Search for "devenv.exe xxx YourApplicationName..." and select it
Click "Attach"
Menu: Debug | Exceptions..
Tick all the boxes in the thrown column, then "OK"
Your second instance of VS2010 is not debugging your first instance, including all the custom controls.
Return to the first instance of VS2010, and repeat the actions that caused the error in the first place, the second instance of VS2010 will break at the line of code that has the error.
You may want to look at this link there is a bug in vs2012
https://connect.microsoft.com/VisualStudio/feedback/details/749901/error-when-i-click-publish-object-reference-not-set-to-an-instance-of-an-object
I am trying to display some text using MessageBox.Show as shown below in a page_load event in ASP.NET. Before anyone jumps on the case why I am using it in ASP.NET, the use is for debugging only on my own dev box for a special need. There's a reference to System.Windows.Forms in the app.
I used it a few years ago so I know WinForm's MessageBox works. I am using .NET 4.0 and VS 2010. I don't think anything related to this function has changed.
MessageBox.Show("Message", "Caption", MessageBoxButtons.OK, MessageBoxIcon.Information, MessageBoxDefaultButton.Button1, MessageBoxOptions.DefaultDesktopOnly); //used also ServiceNotification option
Any ideas why the message box doesn't display? I have only that line in the code.
ADDITION:
I am VERY AWARE of the message box thing implications. It's a temporary thing for debugging only. The line won't go into production. I have no access to javascript. Please put your thought into why it doesn't work instead of why I shouldn't be using it. I have used it before in 2.0 and it does work. I want to know if the newer .NET changed anything or I misused the option.
Direct Answer: it works in Visual Studio's web server , not in IIS.
The web application is hosted in a process that does not have a desktop, so you cant see any messageboxes.
#Tony, if you add System.Winform.dll to your rference, then you will be able to call message box.show at you development machine. But when you deploy it to some live server it will not work. So alternatively, you need to use javascript alerts. For this you can use this
private void ShowMessage(string message)
{
ScriptManager.RegisterClientScriptBlock(control, GetType(),"key","string.format("alert('{0}');",message),true);
}
Back in .Net 2.0 days, you could do this by including system.windows (I think) in your using statement.
Then, in the method, it would be system.windows.forms.Messagebox.show("foo");
I won't presume to tell you "yer doin it wrong"...
Just be aware that this will only show up on the server box, and could cause issues in a production environment.
The alert() is better, and console.log() is even better.
We are getting intermittent problems on a production server that we cannot recreate.
There are two very strange things about the issue. Firstly it's a method not found error on the constructor (ctor) for an exception handling helper class and secondly we have custom errors switched on for remote users and this property is being ignored.
The detail of the error is:
Server Error in '/MyWebsite' Application.
Method not found: 'Void MyExceptionHelperClass..ctor (System.Exception)'.
...
Exception Details: System.MissingMethodException: Method not found: 'Void MyExceptionHelperClass..ctor (System.Exception)'.
...
The stack trace is pretty unhelpful.
My thoughts are that there may be an out-of-memory error or something like that that is killing the page. When the exception handling code kicks in it tries to create an exception object which fails for the same reason giving this error.
However this is wild speculation. We are waiting for the event logs to see whether anything is amiss with the server but in the meantime does anyone have any thoughts or suggestions?
UPDATE:
It has proven difficult to get information out of the team responsible for the production servers but I have managed to find out that as far as load balancing is concerned, this site is currently only running on one server (this can be made to switch over onto another if necessary). Given that this is an intermittent problem and there is only one server involved, then I find it difficult to believe that this could be an assembly issue. Surely if it was then the problem would occur every time?
If you see this error happening on a site that has custom errors turned on, then the error is happening in the custom error handling routine itself.
From the look of the .NET error message it appears that your routine is expecting a constructor that accepts an exception by reference - your comment above shows a constructor that accepts by value.
Check carefully that there isn't a stale version of an assembly in your system somewhere. These can lurk in the Temporary ASP.NET Files folder; you'll need to do an "iisreset /stop" before you can clear them out.
In that regard it's always a good idea to make sure that AssemblyInfo.cs is set up to automatically stamp version numbers in some way. We have our version numbers tied to our source code repository system and CI build box so we can tell exactly what was in what assembly really easily.
I would use elmah: http://code.google.com/p/elmah/ to hopefully give you a bit more insight into the issue. It is free and can be used on an existing site without any recompilation. Try it - and post back if the issue is still happening.
As others have also mentioned, I would suspect that your site is somehow using an out of date version of an assembly. Something you could try doing is a full Precompile of your site before deploying to your production server. This ensures that ASP .Net doesn't dynamically compile the site on the fly, and therefore should mean that it's using completely up to date code throughout.
Do you have a no parameter public constructor defined for MyExceptionHelperClass in your code? Or is the class meant to only have static methods, in which case it should be a static class.
public class MyExceptionHelperClass()
{
public MyExceptionHelperClass() { }
}
Unfortunately, this may be one of those cases where the error message is of little to no value. In my experience, this general class of exception may be the result of either a configuration issue or bad logic aroung threading/app domains. For example, I have seen similar issues upon attempting to load the same assembly into an app domain more than once.
You mention that this is difficult to reproduce. If it's only happening on one server in the production farm it's more likely to be a config issue (with that machine). If it's happening on more than one server than it could be either config or threading.
It might be worth spending some time looking at the larger code base around the areas mentioned above. The root cause may not be in this class. Good luck!
I think it's a Framework issue with keeping compiled versions consistency. It's common to see same sort of errors while updating site sources repeatedly. Just try something like
net stop iisadmin /y && del /q /f /s "%systemroot%\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\*.*" && iisreset
I encountered this exception today on a webforms page. I found a solution, but I'm not sure why it worked.
Nest the code behind in a 'Namespace [YourNamespace]' tag.
Add the namespace to the html Page tag's Inherits property in the aspx page 'Inherits="PathStart.YourNameSpace.ClassName"'.
Rebuild
Navigate to the page again and you should not encounter the exception.
After following the steps above I reverted the changes and did not re-encounter the exception.