HTTP 412 Precondition Failed Error - Meaning & Fix
The HTTP 412 Precondition Failed error occurs when a request to access a resource is denied due to unmet preconditions set by the server. This typically involves failed conditions in headers like If-Unmodified-Since or If-None-Match. The server cannot process the request, usually related to resource modification or upload.
Main causes
Conditional request headers such as If-Unmodified-Since or If-None-Match are used in the request, and the conditions specified don't match the current state of the resource.
Attempting to modify or update a resource that has been changed since the timestamp provided in the If-Unmodified-Since header.
Sending a request with an If-None-Match header containing an ETag that doesn't match any of the current ETags for the resource.
Using methods other than GET or HEAD on a resource that requires specific precondition headers which aren't met or are absent in the request.
# Request example curl -X POST https://sandbox.oxylabs.io/ -H 'Accept: application/xml;q=0.9' -H 'Accept-Encoding: br' -H 'User-Agent: AppleWebKit/537.36'
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Common fixes
Ensure the request data is correct and doesn't conflict with existing data.
Implement version control checks to handle concurrent data updates.
Use unique identifiers or timestamps to manage data synchronization.
Review and adjust the resource's update and conflict resolution logic.
# Response example HTTP/1.1 412 Precondition Failed Content-Type: application/xml Content-Encoding: br412Precondition Failed
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