Runtime errors for Web Forms applications are often posted in the client browser.
The “Object reference not set to an instance of an object” error message might display in a client browser for a Web Forms application if the application uses an unsupported version of the .NET Framework. The error message description indicates that “an unhandled exception occurred during the execution of the current web request,” and the exception details display a “System.NullReferenceException”.
You can resolve this type of error by opening a command window on the server, changing directories to the Microsoft.NET\Framework\v2.0.50727 directory in the Windows system path, and typing the following command: aspnet_regiis -i. This upgrades all IIS scriptmaps to use the 4.0 release version of ASP.NET. After running this command and restarting the server, the error message should no longer display.
This error is usually due to an incorrect ASP.NET or IIS configuration setup. To resolve this issue, make sure .NET Framework 4.0 is installed on the server computer, register ASP.NET 4.0 with IIS by running aspnet_regiis.exe -I from the .NET Framework 4.0 directory, and make sure ASP.NET 4.0 is the version set for your Web application in the IIS Manager. You might also need to restart IIS.
This error can be caused by different versions of PowerBuilder .NET assemblies in the server environment. To resolve this issue, remove extra copies of PowerBuilder .NET assemblies from the Global Assembly Cache (GAC), leaving only the latest copies of each assembly.
This error is also known as the “404 file not found” error. If you see this error, make sure all the application files and folders have been generated under the wwwroot directory on the IIS server computer. If you are using a TCP port number other than 80 (the default port number), you must include the port number in the URL for the Web Forms application.
If you are trying to open the page from a remote client, ping the server to make sure it is accessible. If the firewall is on for the server you are accessing, turn it off and open the page again.
After successfully deploying a Web Forms application, you might see an error such as the following when you try to run the application: System.IO.FileNotFoundException: The specified module could not be found. This is typically because IIS cannot locate PowerBuilder runtime DLLs, such as pbdwmversion.dll or pbshrversion.dll, or the Microsoft Visual C++ runtime libraries msvcr71.dll, msvcp71.dll, msvcp100.dll, msvcr100.dll, and the Microsoft .NET Active Template Library (ATL) module, atl71.dll. To resolve this issue, make sure the DLLs are available on the server and that the directory where the DLLs are located is included in the system path on the server.