[2.03b1 4.3] Can't copy files from /sdcard to /system

[siealex]

After updating to Android 4.3 (Paranoid Android 3.99) I can't copy any files from /sdcard (or /storage/emulated/0) into /system (sometimes backwards too). TC throws an exception: couldn't read source file. But I can copy files from /data (e. g. from /data/local) to /system. What's this?
Also I sometimes can't edit files in a system or data folder if the files have an "x" attribute (e. g. rwxr-xr-x) and the folder itself does not have it.

[ghisler(Author)]

Sounds like root does not have read rights for the files in /storage/emulated/0 on your system. This is necessary so su can copy the file to /system.