Repeat steps from MDL-76865 , which are: Using a fresh installation from the latest weekly release branch... Add a new File cache store instance called "local_file", set the directory name to an empty directory (e.g. "/tmp/muc") and tick auto create directory option if required. Add another new File cache store instance called "stacked_file", set the directory name to a different empty directory (e.g. "/tmp/muc2") and tick auto create directory option if required. Edit the core/coursemodinfo definition store mappings and set the primary store to local_file and the final store to stacked_file. Create a new empty course page, no need to add any activities. Change the default "General" heading of your new course page using the in-place editor to prime both cache stores. Remove any directories inside /tmp/muc/core_coursemodinfo to clear the local cache, but leave the stacked cache primed. Change the section 1 heading a second time. Before fix: Observe the web service request to core_update_inplace_editable takes a very long time to return anything (Maximum lock wait time * number of store instances) without this patch. After fix: The web service returned promptly and the section heading updates without a long wait, as in step 5.