Hello, I'm hitting my head against a wall since a couple days ago. Last paragraph has the big question, the rest is context.

I run a fairly big Wordpress blog, with a somewhat convoluted configuration rewriting legacy URLs that follow me since 2002. I use extensive caching via plugins that pregenerate HTML on disk and I rewrite requests to serve HTML instead of talking to PHP. Everything worked well until a domain change.

Yesterday after I replaced the domain in the various configuration files, nginx started sending every request to the PHP processor. The location / is pretty standard:
location / {
try_files cache_path$uri $uri $uri/ /index.php;
}

Everything in the paths exists and has the correct permissions, but nginx keeps sending everything through /index.php and killing my server via a 180-200 load average.

I tried everything googleable, but I can't detect WHY nginx goes that route. The debug log shows a lot of not matching rules/regexes but there's nothing I can do to follow the decision tree that nginx follows to end in PHP. Is there anything I can do to at least simulate the directive processing?

Thanks in advance.