Just updated to Moodle 3.2.1+ (Build: 20170209) - this problem existed before and after.
I have an error message on my notification screen:
The following plugins in your system are using Events 1 API deprecated handlers: ''. Please, update them to use Events 2 API. See https://docs.moodle.org/dev/Event_2#Event_dispatching_and_observers.
Note that the list of plugins is empty. I have very few add-ons in our Moodle installation.
Possibly related, when I check for updates, I get this:
core_plugin/err_response_empty
Having read the associated document, I checked that each plugin in our system mod folder had a version.php. They all did.
In addition, I checked the database table and it matches the list of sub-folders in that mod folder. There do not seem to be any non-standard folders there. Whenever I do an update, I delete everything and reinstall from the downloaded clean installation file. The only add-ons we have are one theme, an auth plugin and an enrol plugin -- both of which I've checked and seen that they also have a version.php file.
Since this existed before and after, I thought to check the database, but don't want to touch much. I just looked and the list looks right. Very confused.
I do not know what else to check. Thoughts? Suggestions?