"404 - File or directory not found" error received when trying to log into MailEssentials

Overview

After uninstalling .NET 4.8 and re-installing version 4.7 you cannot log into the MailEssentials configuration page and it generates the following error:

Server Error
404 - File or directory not found.
The resource you are looking for might have been removed, had its name changed, or is temporarily unavailable.

The login page displays a "Server Error in '/' Application. The resource cannot be found"  as in the image below:

Solution

If IIS is configured to use the correct .NET version, the solution is to switch the User interface mode from IIS to local and back to IIS.

This action will reset the IIS and the settings, which in turn will recreate the websites and application pools.

Testing

Resetting the user interface as described above will allow you to access the MailEssentials Configuration UI.

If the issue still persists, please generate the troubleshooting logs as follows:

• Make sure that you have tracing enabled.
• Wait for at least 30 minutes to gather enough information and for the issue to be reproduced.
• Run the troubleshooter:
  1. Start > Programs > GFI MailEssentials > Troubleshooter
  2. Follow the Log Generation Wizard for collecting the required and pertinent information.
  3. Select New Case when completing the log generation to attach the logs to a new case that will be automatically created, or open a support ticket manually and attach the logs to that ticket, so that the Support team can investigate the problem.