Session error: "Query error: Commands out of sync; you can't run this command now..."

maybe you should investigate on this query: SELECT RELEASE_LOCK('868db8ea6235235edrgydrfg6b5d33ea77') AS ci_session_lock

This is a query from the standard Session core file of the CI library, not a query from the application.
If the problem is in the core of Codeigniter files then someone would face the same problem and this is why I ask on the forum to find a solution.