To fix this issue, follow the below steps:
1. RDP into the server.
2. Go to %plesk_dir%/Mail servers/Mailenable/Bin
3. Run the “meinstaller.exe” utility
4. Execute option 13 – “Reset IIS virtual directory configuration settings
for ASP/ASPX”
5. The installer will prompt for the framework to be set, choose the 2.0
framework in the dropdown menu.
6. Complete restart IIS.
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