Sems to be quite obvious: query value 'upload' is one cause.
https://forums.modx.com/thread/95047/evo-1-0-15-kcfinder-problem#dis-post-515268
Not sure, wether the changed upload script is another.
?Is it possible to suggest an update so that the Mod_Security doesn't flag this anymore?
Mod_security isn't running on my Rackspace Cloud Site and uploads still don't work, so something else is blocking uploads. I'm not alone in this
https://github.com/modxcms/evolution/issues/371