Unexpected Error: The underlying connection was closed

Hi MercuryMan,

For troubleshooting this issue, you can do as the followings:

1. Compare the differences between your test enviroment and production environment.


2. Compare the web.config file


3. Add a log to each line code check which line code may cause this issue.


4. Debug the code

Best Regards,

Wendy

Forum Support

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Wendy Li

TechNet Community Support