- Software and digital services
- HTTP service
409
HTTP 409 Conflict: the request conflicts with the resource’s current state
Risk level
Low
Usually safe to check without specialist tools.
Urgency
Medium
Quick answer
HTTP 409 means the request could not be completed because it conflicts with the current state of the target resource. The server should provide enough information to recognize the conflict.
Safety first
Stop and check this first
- Do not force an overwrite or repeatedly submit the same write until the current resource state and the conflicting change are understood.
Safe checks you can perform
- Read the conflict details returned by the server
- Fetch the current resource state before resubmitting
- Resolve the difference deliberately
Leave these tasks to a qualified professional
- Do not attempt this professional task: Review concurrency and conflict reporting
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Review concurrency and conflict reporting
What they doThe API owner should verify version checks update semantics and the response details needed for a client to recognize and safely resolve the conflict.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Read the conflict details returned by the server
Preserve the response content request identifier and timestamp. Look for the resource version state or field that the server says conflicts.
Redact credentials personal data and private resource content before sharing the response.
Evidence: RFC 9110 section 15.5.10 - 409 Conflict
Fetch the current resource state before resubmitting
Use a safe read operation to obtain the current representation then compare it with the state on which the failed update was based.
Do not overwrite newer changes merely to remove the conflict.
Evidence: RFC 9110 section 15.5.10 - 409 Conflict
Resolve the difference deliberately
Merge the intended change with the current state or ask the user which version should win then submit the corrected request once.
Repeating the unchanged request can reproduce the conflict or discard another user’s work.
Evidence: RFC 9110 section 15.5.10 - 409 Conflict
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Software and digital services
- Brand
- HTTP
- Product type
- HTTP service
Known code variants
- 409 Conflict
- 409 Conflicto
- 409 Conflitto
- 409 Konflikt
- code erreur 409
- HTTP 409
- HTTP status 409
- status code 409
What it means
The response indicates a resolvable state conflict but does not prove that a retry with unchanged data is safe or useful.
Warnings and stop conditions
- Higheditorial warning
Do not force an overwrite or repeatedly submit the same write until the current resource state and the conflicting change are understood.
Evidence: RFC 9110 section 15.5.10 - 409 Conflict
Symptoms and causes
Probable causes · in order
- The request conflicts with the resource’s current stateConfirmed
RFC 9110 defines 409 as a request that cannot be completed because of a conflict with the current state of its target resource.
Evidence: RFC 9110 section 15.5.10 - 409 Conflict
- A submitted version conflicts with a newer changePossible
The standard gives a versioned PUT whose changes conflict with an earlier third-party request as a likely example of 409.
Evidence: RFC 9110 section 15.5.10 - 409 Conflict
Virtual technician
Does 409 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
RFC 9110 section 15.5.10 - 409 Conflict
Internet Engineering Task Force · 2022 · official_doc
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