I'm not really sure what the error means, but a couple of questions:
- Are you Stg & UAT on the same version?
- Are both Stg & UAT configured the same, i.e. where they recently refreshed from your PROD
If neither of these apply I'd probably suggest contacting support to see if they can help.
Firstly i want to think you for your answer. My Stg and UAT are on the same version and configured the same. Now i have no more this problem, i was told that its maybe a connectivity problem.