JavaScript download fails after large AJAX payload: ERR_HTTP2_PROTOCOL_ERROR

Sending an AJAX request with a large JSON payload (e.g. >100 items) from the frontend, but the browser reports net::ERR_HTTP2_PROTOCOL_ERROR. Smaller payloads work fine. What gives?

This error often reflects an overly long Request URI or header limits, especially when the request is encoded in querystrings or headers ([turn0search18](Microsoft Learn+15Stack Overflow+15GreenGeeks+15). Why it happens: • Browsers send huge URIs or query parameters via long GET requests, which may exceed server or HTTP/2 header size limits. • Some servers interpret long URIs as invalid and reset the stream rather than return standard 414 / 431 errors, resulting in protocol-level failure. Fixes: • Switch from GET to POST for large JSON payloads—send data in request body. • Increase proxy or server http2_max_header_size and http2_max_field_size thresholds ([turn0search10](ItsMyCode+1CSDN Blog+1).

🧷 Tags javascript, ajax, http2, ERR_HTTP2_PROTOCOL_ERROR, large-payload, nodejs, headers, uri-length