I am getting MySQL errors from my DeskPRO On-Premise install very few minutes. They say that 'an exception occurred while executing' various queries. After the query is the line:
SQLSTATE[HY000]: General error: 3 Error writing file X (Errcode: 28)
SQLSTATE[HY000]: General error: 1030 Got error -1 from storage engine
where X is a temporary file of some kind. What is causing this?
This means MySQL is running out of disk space when it tries to write a temporary file.
Increase the disk space available to MySQL. Even if it appears that there is still space available on the disk, it's best to leave a minimum of 10GB free.