System.Data.OleDb.OleDbException: Unspecified error - asp.net

Question

I'm Totally new in ASP.net and currently working on a CRM application. This project uses .mdb files as backend but I am getting the following runtime error:
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.Data.OleDb.OleDbException:
Unspecified error
Stack Trace:
[OleDbException (0x80004005):
Unspecified error]
EmployeeManager.isUser(String strUID,
String strPswd) in
d:\hosting\nitindia\App_Code\EmployeeManager.vb:481
Employees.BtnSubmit_Click(Object
sender, EventArgs e) in
d:\hosting\nitindia\Employees.aspx.vb:35
System.Web.UI.WebControls.Button.OnClick(EventArgs
e) +111
System.Web.UI.WebControls.Button.RaisePostBackEvent(String
eventArgument) +110
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String
eventArgument) +10
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler
sourceControl, String eventArgument)
+13 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection
postData) +36
System.Web.UI.Page.ProcessRequestMain(Boolean
includeStagesBeforeAsyncPoint, Boolean
includeStagesAfterAsyncPoint) +1565
The above error occurs only when we upload these pages & test online. When running on localhost the error is not being raised.
What is the cause of this issue, and solution?

Answer 1

System.Data.OleDb.OleDbException: Unspecified error
This error mostly belongs to permission error, for this error we have mutiple solutions as per situation
Put the impersonate=false in web.config file.
If you want to put the impersonate = true in that case you need to provide the read/write permission to impersonate user on "C:\Documents and Settings\server name\ASPNET" folder or through process monitor utility you can check which file don't have sufficient permission.
If you have windows server 2008 then you will not found the ASPNET folder and still want impersonate=true then you need to change the configuration in IIS 7.5/7.0.
Go to IIS -> select your application pool -> Advanced Setting -> Process Model ->Identity=ApplicationPoolIdentity
Go to IIS -> select your application pool -> Advanced Setting -> Load User Profile = False
See here for more details.

Answer 2

Both of these conditions may cause this (rather unhelpfully named) error to occur:
The ASPNET account not having permissions to open the file.
The database file is locked by another user.

Answer 3

for answer finders :
try to look into https://learn.microsoft.com/en-us/iis/application-frameworks/running-classic-asp-applications-on-iis-7-and-iis-8/using-classic-asp-with-microsoft-access-databases-on-iis#using-process-monitor-to-gather-more-information and set Permissions on the Temporary Folders
PS in my case it was impersonate user who does not have access to current user temp folder C:\Users\`Username`\AppData\Local\Temp\