Can not post a reply "Sorry, an error has occurred"

I searched, but found nothing related to my issue.

When posting a reply, I get “Sorry, an error has occurred” and the reply is grayed out. Upon refreshing the page, the reply is not shown.

My error log shows:
170343720 Job exception: undefined method `every’ for Jobs::MigrateUploadScheme:Class

So this apparently has been going on for awhile. My forum is no longer very active for new posts and replies, but has a lot of traffic as it is used as an information resource.

I tried restarting the host and the issue persists.

I am running an older version, 1.6.8 as until now I have had zero issues with this version.

Please help.