Unable to upload images

[bartos92]

Guys im really stuck. I wasnt able to find anyone with the same problems that is why i am creating a topic.

The problem is: everytime I try to upload a image I get this error: 

http://puu.sh/poY90/1cbeb1cde9.png (Unexpected token < in JSON at position 0)

This is what my console says: http://puu.sh/poYbf/bbd41e7271.png

index.php?controller=AdminModules&token=150b98d…&configure=ptssliderlayer&s…:1617 The specified value "" does not conform to the required format.  The format is "#rrggbb" where rr, gg, bb are two-digit hexadecimal numbers.
index.php?controller=AdminModules&token=150b98d…&configure=ptssliderlayer&s…:1901 The specified value "" does not conform to the required format.  The format is "#rrggbb" where rr, gg, bb are two-digit hexadecimal numbers.
index.php?controller=AdminModules&token=150b98d…&configure=ptssliderlayer&s…:1906 The specified value "" does not conform to the required format.  The format is "#rrggbb" where rr, gg, bb are two-digit hexadecimal numbers.
3jquery-1.11.0.min.js:3 The specified value "" does not conform to the required format.  The format is "#rrggbb" where rr, gg, bb are two-digit hexadecimal numbers.

I think this problem is maybe introduced by migrating to another server, so I moved the files with an FTP client. Maybe some file went missing or i dont know. Help is appreciated!

[shacker]

ok, first, haev you a module in the watermark hook or watermark installed? if yes, in modules -> positions remove all from watermark section