Apache error 500 on large file uploads (mod_security)
As far as I've tried, none of the usual solutions works for me. Well, my problem, I'm receiving an 500 Error every time I upload a "large file" (600 KB ~), with smaller images it works fine. So..., even with this (extreme) .htaccess file it keeps happening, and yes, .htaccess are active:
upload_max_filesize = 100M
post_max_size = 100M
memory_limit = 128M
max_input_time = 6000
max_execution_time = 6000
So, I take a look at the logs and find this (is only one line, just pasted it as easy to read with line jumps):
[Mon Jul 27 17:09:28.<port> 2015] [:error] [pid 21423] [client <ip>]
ModSecurity: Access denied with code 44 (phase 2).
Match of "eq 0" against "MULTIPART_UNMATCHED_BOUNDARY" required.
[file "/etc/httpd/conf.d/mod_security.conf"]
[line "35"] [id "<another id>"]
[msg "Multipart parser detected a possible unmatched boundary."]
[hostname "<my host>"] [uri "<my script>"] [unique_id "<id (useless I think)"]
But, now I not able to find how to edit the mod_security (it has the default config, and empty activated_rules) config in order (i think) to allow this "large" file uploads. I'm running PHP 5.3 in Apache 2.4/CentOS 7.
Answer
The fact you have a ModSecurity alert means that you can't have empty activated_rules folder or you are including the rules in some other way.
There are known problems with ModSecurity for this error and it seems very susceptible to false positives.
The main advice when I rule is raising too many false positives is to just turn off that rule (I'm assuming it's rule 200003 that's firing but replace the id as appropriate):
SecRuleRemoveById 200003