Saving the options again will not reset the state; it will only update the list of options that need to be rebuilt by the settings rebuild task.
It can be manually reset with a MySQL query:
Code:
UPDATE vw_defer
SET hold = 0
WHERE hold > 0
We set a failed state on a given task-type (here, "settings") when a rebuild request set a unique lock over 60 seconds ago. If the lock has not been released yet, we assume that either the PHP timeout was reached or an error occurred. We assume that running the same task again will result in the same errors, so it is placed "on hold"; if we did not assume this, a denial of service condition would be started, infinitely retrying deferred.php (see:
VWE-2014-0383). Normally, developer attention is required to resolve the underlying issue that triggered the error, so failed states are reset by running the upgrade script (in case the bug fix was part of the upgrade).
When a notice is added to this setting, it would be useful to state whether the rebuild has failed, to provide information about how to look into it, and to provide an easy way to try again.