I’ve got the same problem.
Some people suggested de-activating/deinstalling the automatic upgrade plugin.
I did that, but the error persists.
Some people think it’s the server
https://www.ads-software.com/support/topic/242642?replies=12
but my server-guys are not sure… yet… hopefully.
Anybody any ideas, please?
update: I successfully tried deactivating ALL plugins. Then update automatically worked.
Afterwards needed to reactivate all plugins, and enter WP API Key for Blog Stats plugin.
I am happy now, but it was quite painful!
Cheers,
Claus