This Error occurs when using crystal reports as web reporting.
There are several reasons for this.
- Required DLL are missing in web setup
- Required Reports files are missing in web setup
- Access Permisions
To over come this you can create web setup as below (VS2008)
Go to Other Projects , Add Web Set up Project.
Then Right Click the Project and goto Properties and then Prerequisites and select
crystal Reports Basic for Visual Studio..
And add other files (sometimes reports files are not including please be careful)
Note:- If your error is still occur use filemon (google it and get the first link) and monitor your files when browsing. it will give what is the actual cause of the error.
Give full permission to asp.net (give permissions in IIS , Windows/Temp, wwwroot )