HTTP 407 Proxy Authentication Required vs 412 Precondition Failed
Both HTTP 407 (Proxy Authentication Required) and 412 (Precondition Failed) belong to the 4xx Client Error category. 407 indicates that the client must first authenticate itself with the proxy. Meanwhile, 412 means that one or more conditions in the request headers (If-Match, If-Unmodified-Since) evaluated to false.
Description
The client must first authenticate itself with the proxy.
When You See It
When accessing the internet through a corporate proxy that requires authentication.
How to Fix
Configure proxy credentials in your HTTP client or browser settings.
Description
One or more conditions in the request headers (If-Match, If-Unmodified-Since) evaluated to false.
When You See It
When using conditional requests with ETags and the resource has changed.
How to Fix
Refresh the ETag/Last-Modified value and retry with updated preconditions.
Key Differences
HTTP 407: The client must first authenticate itself with the proxy.
HTTP 412: One or more conditions in the request headers (If-Match, If-Unmodified-Since) evaluated to false.
You encounter 407 when when accessing the internet through a corporate proxy that requires authentication.
You encounter 412 when when using conditional requests with ETags and the resource has changed.
When to Use Which
For 407 (Proxy Authentication Required): Configure proxy credentials in your HTTP client or browser settings. For 412 (Precondition Failed): Refresh the ETag/Last-Modified value and retry with updated preconditions.