This started happening when I flashed 4.4 CM, but I also had hardware replaced on my phone around the same time. This makes it harder to diagnose.
What I've done, to no avail:
- clear phone data / cache
- full data wipe
- reinstal lAOSP camera apk
- /cameradata fix from xda thread
- Clean flash new ROM
- Restore AOSP & TW ROMS
- Odin to barebones 4.1 stock
Camera app still can't connect. Since I Odin'd back to stock, and problem still persist -- I believe it's a hardware issue. Like a misaligned pin connecting the camera. I'm going to have it looked at, but opened a thread to get any reassurance or alternative suggestions.
I typed in *#22745927 to enable hidden menus, and then *#0*# for General Test Mode. The "Mega Cam" (Back-facing) still has same error message. I strongly think it's hardware now.