Symptoms
Plesk shows the following error after login:
ERROR: bad arguments (key_info.php:32)
Cause
Corrupted license key file. The same error may appear when clicking on Retrieve if a license was terminated on a licensing server side, but was still in use in Plesk.
Resolution
Regenerate license key file. In order to do that, install production license using the following CLI command:
plesk bin license -i XXXXXX-XXXXXX-XXXXXX-XXXXXX-XXXXXX
where XXXXXX-XXXXXX-XXXXXX-XXXXXX-XXXXXX is a license key number.