Symptom

Getting the following error message in web browser when trying to run custom web application in Visual Studio.

Environment

 Using BarTender 2016 and later, 64 bit

Running custom web application in Visual Studio.

Fix/Answer

If your custom web application is compiling fine without errors, and this error is occurring within the web browser in Visual Studio, usually the bit version is not set correctly for IIS Express. Check the following in Visual Studio:

• In Visual Studio go to tools->options->projects and solutions->web projects->enable the option for “Use the 64 bit version of IIS Express for web sites and projects” (This may vary depending on the version of Visual Studio you use).

More Information

Example: The options as seen in Visual Studio 2019