HTTP 405 Method Not Allowed
The HTTP method (GET, POST, etc.) isn't allowed on this URL. The resource exists; you used the wrong verb.
What it means
405 says "this URL is valid, but you can't use that HTTP method on it." Sending POST to a read-only endpoint, GET to a webhook receiver, DELETE to an endpoint that doesn't support it — all common 405 triggers. The response must include an Allow header listing the methods that are accepted.
Common in monitoring when someone changes the monitor type from GET to POST without updating the URL, or when an endpoint was historically idempotent and got tightened.
Common causes
- Monitor configured to use POST against a GET-only endpoint
- Read-only endpoint receiving a write request
- Webhook receiver hit with GET instead of POST
- Static asset hosting that only allows GET / HEAD
How to fix it
- 1Check the Allow header in the 405 response — use one of those methods
- 2Update the monitor or client to use the correct HTTP method
How Uptimera reports 405
Uptimera flags 405 as down. Confirm your monitor is configured with the right HTTP method for the endpoint.
Catch 405s before your customers do
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