There's no error message or any further information in that log? I didn't see any such errors during my tests. Please PM backend super users login credentials and will review the log.

Have reviewed your install. The earliest output of that error being on 02/12/2020 20:12:03. It's not really an error though. It's just a function call is failing to load an object with an id of 1, but it doesn't seam to be negatively impacting the activation of subscriptions.

Was all that changed at the time is CBSubs being updated? Did you used to have other payment gateways than QuickPay and have deleted them? If so you may have records in the database still referencing those old payment gateways and when CBSubs goes to check those records (typically in the case of an Upgrade it will check their past subscription record) it's failing since the previous gateway doesn't exist anymore.

Yes, that would be when CBSubs QuickPay recurring behavior was fixed, but I don't see anything in the fixes that could be causing this. It might be caused by other changes in upcoming CB Paid Subscriptions 4.5.0 release. I'm also still unable to reproduce this issue, but will continue to investigate. It at least does not appear to be negatively impacting the activation of subscriptions.

Ok, believe this is due to the callback url configured in your QuickPay account. At QuickPay navigate to Settings > Integration and empty the "Callback url" parameter. We send this with every payment so it's not necessary to configure that anymore. If you do want to configure it be sure you've used the full URL provided within your QuickPay gateway.