Error 1036 occurs when a Cloudflare Transform Rule generates a rewritten URL that is too long. Cloudflare enforces a maximum length for rewritten URLs to prevent abuse and ensure compatibility with origin servers and other network devices. If your rewrite rule appends data to the path, adds excessive query parameters, or concatenates long strings, the resulting URL may exceed this limit.
The Transform Rule concatenates multiple values or long strings to the URL path or query string, pushing the total length over the limit.
Multiple Transform Rules chain together, each appending to the URL, causing it to grow with each pass until it exceeds the length limit.
The original request URL is very long, and even a small rewrite pushes it over the maximum.
Review your Transform Rules and estimate the maximum possible length of the rewritten URL. Cloudflare enforces a limit of approximately 16 KB for the entire URL.
Reduce the amount of data appended in the rewrite. Consider moving long parameters to request headers instead of the URL.
Verify that multiple Transform Rules are not unintentionally building on each other's output, making the URL longer with each rule.
A Cloudflare Transform Rule or rewrite produced an invalid URI path.
A Cloudflare Transform Rule's expression could not be evaluated at runtime.
A Transform Rule attempted to modify a request header that Cloudflare does not allow to be changed.