When a user wants to log into Plesk Panel you get a message. There are some points a user comes across. The most important file named filename.php is part of Plesk distribution. It cannot be run outside of Plesk environment. This can cause two things .php file can not be decrypted by Plesk engine or .php file can not be decrypted if:
1. Plesk key installed is not valid. It means that you could install key for Plesk for Linux not for Windows or something else.
2. Plesk php environment is corrupt.
Remove Error message while you are logging in to Plesk panel solution. To fix the first case you need to do the following:
a. You have to close the browser you where using. Or just make sure that your browser does not show cached web pages.
b. Then Stop the Plesk Control Panel Service.
c. Remove all files from within %plesk_dir%PrivateTemp
d. Reset current Plesk to default PLSK.00000000.0000. You can do it using defpkey.reg attached to this article.
e. Start Plesk Control Panel Service.
f. Re-upload valid Plesk key straight via Plesk Panel. You can upload PLSK.XXXXXXXX.XXXX.exe key.
To fix the second case you need to do the following: Switch Plesk web server to another. If IIS is used as Plesk web server switch it to Apache
%plesk_bin%\reconfigurator.exe –switch-plesk-web-server –new-provider=apache. If Apache is used as Plesk web server switch it to IIS
%plesk_bin%\reconfigurator.exe –switch-plesk-web-server –new-provider=iis
Check how you Panel works. If it shows the same message it means that PHP files were changed. In this case you need to run Plesk Repair.