Bad Request

Updating a new theme, I went to Editor > header.php and clicked Update file. This brought me to https://www.xxxxxxxxx.com/wp-admin/theme-editor.php

Bad Request

Your browser sent a request that this server could not understand.

I tried a few times. I like the theme but but doesn’t like me. I’m off to find a new one but am curious why it would do this.

Edit: I went to check error logs. Now I’m REALLY confused! I’ll dump ths theme for sure

[Tue Dec 17 15:42:53 2013] [error] [client 173.********] ModSecurity: Warning. Pattern match “(?:\\b(?:(?:type\\b\\W*?\\b(?:text\\b\\W*?\\b(?:j(?:ava)?|ecma|vb)|application\\b\\W*?\\bx-(?:java|vb))script|c(?:opyparentfolder|reatetextrange)|get(?:special|parent)folder|iframe\\b.{0,100}?\\bsrc)\\b|on(?:(?:mo(?:use(?:o(?:ver|ut)|down|move|up)|ve)|key(?:press|d …” at ARGS:newcontent. [file “/etc/httpd/modsecurity.d/modsecurity_crs_40_generic_attacks.conf”] [line “102”] [id “950004”] [msg “Cross-site Scripting (XSS) Attack”] [data “<meta”] [severity “CRITICAL”] [tag “WEB_ATTACK/XSS”] [hostname “www.xxxxxxxx.com”] [uri “/wp-admin/theme-editor.php”]

(no clue what it means but CRITICAL tells me to delete)