We raised this back in August via email and there hasn't been much progress. The last message we received was on the 3rd of October. I'm raising this here too in the hope you can help us.
Barclays mentioned incident number INC1014345207.
Here's a description of the issue:
We've had an increased amount of clients reach out to us as their end users are seeing 6004 errors when trying to connect via our services.
According to your FAQs here (https://www.barclays.co.uk/help/online-banking/login/what-does-error-code-6-mean-/), you advise your users to clear cache and retry however this never resolves the issue.
We've attached some end-user screenshots for your reference.
Can you please advise what the root cause is?