Apache mod_rewrite internal redirect loop detected

When implementing URL rewriting with mod_rewrite, the Apache error log may show a message about detecting an internal redirect loop. This occurs when a RewriteRule's substitution pattern unintentionally matches the original rule again, causing repeated internal processing.

The goal is to design rewrite rules that avoid self-referential matches while still achieving the desired URL transformation. The challenge is that some legitimate use cases, like language-based routing or proxy setups, may require multiple internal redirects.

How can RewriteRule conditions be structured to prevent accidental recursion without breaking complex transformation chains? What are the specific patterns that commonly trigger this error, and how can they be refactored?