{"id":37083,"date":"2025-06-03T13:57:04","date_gmt":"2025-06-03T13:57:04","guid":{"rendered":"https:\/\/www.resellerclub.com\/blog\/?p=37083"},"modified":"2025-07-07T13:08:28","modified_gmt":"2025-07-07T13:08:28","slug":"what-is-412-status-code","status":"publish","type":"post","link":"https:\/\/www.resellerclub.com\/blog\/what-is-412-status-code\/","title":{"rendered":"What is 412 Status Code?"},"content":{"rendered":"

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The 412 status code, also known as “412 Precondition Failed”, is a client error response indicating that access to a requested resource has been denied. When a client makes a request with specific conditions and these conditions are not met, the server returns HTTP status 412 Precondition Failed. <\/p>\n

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This commonly occurs during resource modifications or uploads, where the server needs to ensure data consistency and prevent conflicts between multiple users trying to modify the same resource simultaneously.<\/p>\n

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What Causes the 412 Status Code?<\/strong><\/h2>\n

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The 412 response code typically occurs in several scenarios:<\/p>\n

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  1. Resource Version Mismatch<\/strong><\/li>\n<\/ol>\n

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    When the ETag (entity tag) sent in the request does not match the current version on the server, indicating the resource has been modified since the client last accessed it.<\/p>\n

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    1. Conditional Headers<\/strong><\/li>\n<\/ol>\n

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      When requests containing If-Match or If-Unmodified-Since headers fail their conditions. This is particularly important in preventing “mid-air collisions”, where many users attempt to modify the same resource simultaneously.<\/p>\n

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      1. Resource State Changes<\/strong><\/li>\n<\/ol>\n

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        When the requested resource’s state does not match the client’s expectations, it often occurs during content updates or file uploads.<\/p>\n

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        Example<\/strong><\/h2>\n

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        Here’s a practical example of a request and response resulting in a 412 Precondition Failed:<\/p>\n

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        Request:<\/strong><\/p>\n

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        POST \/document\/edit\/123 HTTP\/1.1\n\nHost: example.com\n\nIf-Match: \"abc123def456\"\n\nContent-Type: application\/json\n\nContent-Length: 50\n\n{\n    \"title\": \"Updated Document Title\",\n\n    \"content\": \"New content\"\n\n}\n<\/code><\/pre>\n
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        Response:<\/strong><\/p>\n
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        HTTP\/1.1 412 Precondition Failed\n\nContent-Type: application\/json\n\nContent-Length: 89\n\n{\n\n    \"error\": \"Document has been modified since the last retrieval\"\n\n    \"current_etag\": \"xyz789uvw321\"\n\n}\n<\/code><\/pre>\n
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        In this example, the client attempts to update the document but includes an outdated e-tag. The server recognises the document has been modified and responds with 412 status, preventing potential loss or conflicts.<\/p>\n
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