AccelerateWP: End user can't activate "Object Cache Module" - Unknown custom object cache plugin is already enabled

Issue

• The end user sees an "incompatible" tag near the activation button, and can't enable the "Object Cache Module" from the AccelerateWP dashboard.
• Cache plugin has recently removed/disabled

Environment

• CloudLinux OS
• AccelerateWP
• WordPress

Solution

Ensure that no "object-cache.php" files are located within the user's wp-content directory. If there are any, remove/rename them.

Cause

Leftover files in the user's directories that conflicts with the AccelerateWP suite.

Useful links

• Allowing module for end-users
• AccelerateWP
• AccelerateWP: End user can't activate "Site Optimization Module" - Found conflicting plugins: Unknown.