Redgate Monitor Base Monitor and Web Server versions are different

Redgate Monitor displays this error when you try to connect from a web server to a base monitor that is a different version.

To fix the problem, you will need to manually remove the base monitor with the incompatible version.

1. On the machine running the web server, go to %ProgramData%\Red Gate\Redgate Monitor\

    - For versions prior to v14 the directory will be  %ProgramData%\Red Gate\SQL Monitor\

2. Open BaseLocation.config and remove the entry for the base monitor mentioned in the error message.
3. Restart the Redgate Monitor website. 

Compatible Base Monitor installer (for your version of web server) can be obtained from Configuration > Base Monitors > Base Monitor installer

Related article:
Moving the Base Monitor to a different machine