I’ve seen that a little while ago in another thread here and I would thus point you to one of this specific thread and @phillxnet’s suggestion:
The first thing to try would thus be:
As to why you are seeing this, an explanation would be:
This warrants the question, then: have you created this task and then updated Rockstor version? You can read more on why I’m thinking that in an older thread:
If the recommendation in the first link provided is not helpful, we can try troubleshooting this further (is it just a specific task causing an issue, or all the scheduled tasks? What does the webUI show for this scheduled task? Is a newly-created task showing the same issue?).
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