Please see the attached, an unusual Plesk Error showing HTML output, suddenly started showing when clicking on Websites/Domains, there is obvious fix mentioned.
pls. consider to POST the complete error - message and avoid a limited screenshot here, because people willing to help you are not able to investigate the whole error message.
In addition, pls. note that the "panel.log" might show MORE details and pls. don't forget:
Sometimes, it is as well a good idea to change the log - level ( TEMPORARILY! ), to get more informations in Plesk - log - files:
Thank you, unfortunately I never got around to testing this as I had to install an additional component (Health Monitor and Spam Assassin) and the error removed itself afterwards!
I will bear in mind if this happens again in the future! Thanks for your help