414 URI Too Long

What’s actually happening

A request fails the moment the URL gets long enough — often a search or filter form using GET that packs dozens of fields into the query string. It can also show up mid-redirect when each hop tacks on more parameters until the URL blows past the cap. Short requests to the same endpoint work fine; only the long ones 414. nginx defaults to an 8k buffer for the request line, so you usually need a genuinely huge URL or a loop to hit it.

Common causes

• A form using method="get" with many fields, so every input lands in the query string and the URL balloons.
• A redirect chain where each hop appends tracking or state params, growing the URL until it exceeds the limit.
• A rewrite loop (.htaccess / nginx) re-appending a query param on every internal pass.
• Encoded data (a base64 blob, a long JWT, a return URL) stuffed into a query parameter instead of the body or a header.
• A server with a deliberately low limit (nginx large_client_header_buffers, Apache LimitRequestLine) set tighter than the app needs.

How to fix it

1. Switch the form from GET to POSTIf a search/filter form is generating a massive query string, change method="get" to method="post" so the data travels in the request body, which isn't subject to the URI length cap. Update the server handler to read POST params.
2. Trim what's in the URLDrop empty/default fields from the query string before submitting, or send only the parameters that changed. Move large blobs (base64, long tokens) out of the URL into the body or a header.
3. Find and break the redirect/rewrite loopTrace it with curl -sIL https://example.com/path and watch the Location header grow on each hop. If a param keeps reappending, fix the rewrite rule so it doesn't re-append on internal passes (check for a missing terminating condition).
4. Raise the server limit if the length is legitimatenginx: bump large_client_header_buffers (e.g. 4 16k) and client_header_buffer_size. Apache: raise LimitRequestLine. Only do this when the long URL is genuinely needed — otherwise fix the root cause.