I had the same problem with OTA.
PcCompanion did update but my Z1c crashed now often.
So I flashed the ftf with flashtool and this time it worked perfect.
I came from .757, rooted and locked bootloader.
Now rooted again with Easy Root Tool v8
Sony Xperia Z1 compact Android 4.4.4
LG-P970 Android 4.4.4
Evisceration Nameless ROM