http-426
Easy Fix
HTTP API · API Responses
HTTP 426 Upgrade Required indicates protocol upgrade required by server for this API request path.
Quick Answer
Error code HTTP-426 on your HTTP API API Responses means: HTTP 426 Upgrade Required indicates protocol upgrade required by server for this API request path.. This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
Likely Causes
How to Fix It
1
Inspect API logs/traces for HTTP 426 with full request/response metadata.
2
Validate request construction against endpoint spec focusing on: protocol upgrade required by server.
3
Fix client auth, payload, headers, or resource assumptions before retrying.
4
Add explicit handling path for HTTP 426 in SDK/service code.
5
Run regression tests to confirm HTTP 426 no longer appears unexpectedly.
Pro Tip
This is a common issue that most users can resolve without specialized tools. Try the first step before moving on to more complex solutions.
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