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ReportHi everyone,
I’m experiencing an intermittent issue in a cloud flow that uses a generic HTTP action to generate a token from ArcGIS Online.
What the flow does
- Uses an HTTP POST request to the ArcGIS Online token endpoint
-
Sends username, password, referer, and f=json
-
Retrieves a token
-
Uses that token in subsequent requests
The Problem
Almost every day the flow fails with this error:
{400 Bad Request
Request Header Or Cookie Too Large}
However, when I:
-
Click Test
-
Run it manually
- It works perfectly again.
No changes are made between failure and success.
Additional Details
-
Method: POST
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Cookies field in the HTTP action is empty
-
I already replaced the HTTP action entirely
-
The issue still returns randomly
-
The problem disappears immediately after manual testing
My Questions
-
Why would the request header or cookie become “too large” when I am not explicitly sending cookies?
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Could Power Automate be accumulating hidden cookies or headers?
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Is there a known limitation with scheduled runs vs manual runs?
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Has anyone seen similar behavior with token-based authentication endpoints?
The strange part is that simply opening and testing the flow fixes it temporarily.
Any insight would be greatly appreciated.
Thanks!
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