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Can you obtain and send us error logs from some of Azure instances?
In case you need more information how to do it, we have knowledge base article about this at:
Having error logs may help us identify the reason for this behavior.
As long the question about load testing, I would recommend to provide some form of warm up of the instances before the actual test.
1. You may do it manually in case you know which URLs get hit by the test.
2. Or you may check with the tool options if there is warm up period. In case of Azure instances I believe that 10 minutes can be safe bet.
3. Also you can see if the tool provides another option - to not start with max number of users but start with 1 and gradually increase the number of users. And again - to start after the warm up.
Also bear in mind that running these test against your Azure account may incur increased fees for it.
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