error/cache/ex configcannotsave

This error can be shown for several related reasons:

• The file system prevented the creation of the directory used for the cache data.
• The directory was created but was not writable.
• The directory was created and is writable, but a file system lock could not be created.

Typically the cache data is stored in $CFG->dataroot in the muc folder. This can be changed in the Moodle config.php by setting the $CFG->altcacheconfigpath setting.

Locks are typically created in $CFG->dataroot in the cache directory. There could for example be a problem creating the lock. This might be because there was a failed install already and the directory needs to be cleared before attempting to install again. It could also be because the file system does not support locking for some reason - although this is unusual.