How much time elapsed while the Replicate tasks were down for server upgrade?
Could it be that the required wall files are no longer available on the source?
Did you try starting by timestamp? That would confirm.
Now, I would hope/expect this major upgrade is just done on a development or QA server, not in prod right?
For the time being you may look at alternative means to handle the (perceived?) Log4j vulnerability. I just disabled the endpoint server in the service configuration file [windows: C:\Program Files\Attunity\Replicate\bin\repctl.cfg ] and removed the module. The Replicate server is likely in a private domain, and the log4j vulnerability is possibly extremely hard or impossible to exploit, but I supposed that will not satisfy the auditors right?