Cannot upload any files and errors.log doesn't work

Hi, I try to install Omeka 2.5 on third server, because there was no possibility to have access to ImageMagick on the first two.
Now the test for Imagemagick shows Success, and everything else seems to work properly, but I cannot upload any files.
I gave full access rights to Files and included folders (777) and each time I try to upload anything I get this message:
You don’t have permission to access /admin/items/edit/3 on this server. >
(of course there is no such directory there…)
I tried to find some trace about errors, so I activated <log.errors = true> and gave full access rights to errors.log file and its directory (application>logs), but nothing is written there - size is zero.

I suspect some URL rewriting problem (.htaccess is standard - the whole site works OK.).

Could you please help me somehow? (I’m not a programmer :slight_smile: )

Finally I received an answer from my hosting support.
It was mod_security - when switched off, files can be added.

I was told that Mod_security can be selectively switched off by inserting into .htacces the following command:

SecRuleRemoveById 300015

I thinh 300015 is my Id as an owner of this server.
But it doesnt work for me - I will solve it later, leaving Mod_security switched off totally.

I Hope this help someone…