While trying to execute an SQL query in PhpMyAdmin versio 4.1.11, the following error appears:
Missing Value from Form
Syntax is correct. The error appears randomly and exactly the same query can be executed successfully next time.
This is PhpMyAdmin internal issue, which is fixed in PhpMyAdmin version 4.1.12. The fix is included into microupdate #40 .
Apply the latest Plesk microupdates .