Bernie's Blog A confusing concoction of Java, mobile devices, technology and photography

Cyanogen Mod: Android Applications And Mismatched UIDs

I recently switched from a vanilla JesusFreke Android ROM to Cyanogen. According to its creator, I would not need to do a wipe of my phone after the upgrade, so I did not (if things do go south, then I'd wipe). My only concern was in my more n00b days, I had Apps2SD installed and I ran it even though JF 1.51 already had a2sd support cooked in. I also had a massive incompatible theme installed. In short, I wasn't so sure my JF1.51 was vanilla enough to survive the switch to Cyanoge without a wipe.

True enough, my worse fears came true. After the flash, everything seemed fine. Things were going great as I got accustomed to the new snappy phone I had. This was until I tried using twidroid. For some reason, it would complain of connection issues, which was not possible as the browser and Market Place connected to the Web just fine. I then proceeded to reinstall the application only to find out that I can no longer install any applications from the Market Place.

To say that this was an extremely rude shock is an understatement.

Lucky for me, watching a nifty Google I/O presentation on how to debug Android thought me a few stuff. logcat for one. (Or did I read that from somewhere else? OK, nevermind that's beside the point)

To do this, I connected the phone to my PC and ran ./adb logcat while doing an install from the Market Place. Logcat showed that an error occured when DalvikVM tried to create its cache in /data/dalvik-cache. For some reasons unknown to me, it just didn't work. I tried checking for permissions but everything seemed fine. There was also a line regarding mismatched application UIDs, but more on that later. At this point, I was freaking out. I did not wanna wipe and reinstall the 40 or so applications (plus, I've gotten quite far in RoboDefence!) I had on my phone.

P/S: I'd like to show the exact error message but unfortunately, I neglected to copy the line from logcat before trying a fix. The successful message is below

I/installd( 1408): move /data/dalvik-cache/data@app@vmdl69624.tmp@classes.dex -> /data/dalvik-cache/data@app@com.twidroid.apk@classes.dex

With the error message, instead of an 'I' your get an 'E' (Info/Error) from installd and the error message is something along the lines of copying to /data/dalvik-cache failed (again, I hate myself for not copying the exact error message. Sorry). Android does not show this error message in your phone, just "Installation failed. Message: ". Yup, a blank message.

I also saw errors regarding mismatched application UIDs, that Android was expecting a certain value but the package being installed was of another. This happened only when I attempted to reinstall an existing application though (in my case, Twidroid).

Here's what I did to fix stuff.

For those familar with Cyanogen, he suggested that if there are any 'weird' issues after an upgrade with installed applications, such as applications disappearing from the Market Place's My Downloads list or you stop getting updates for your installed applications or you get force closes when running applications, you are to run a script called 'fix_permissions' that would... well, fix permissions. Actually, the issue is that Android rebuilds /data/system/packages.xml (with new UIDs) when the ROM is updated and in doing so, there is a mismatch of UIDs between packages.xml and what's in the /data/data directory. For details on what the script does, see this thread.

I ran the script in recovery mode and true enough, the mismatch UID problem went away. I also deleted my /data/dalvik-cache contents just in case there were file permission issues (they get generated again on boot). However on hindsight, I'm not too sure if this helped. Cyanogen has a script called a2sd in the /system/bin/ which does the copying/mounting/permissions during boot anyway.

Anyway, after those 2 steps, my phone was back to normal. Actually, it's really fast and snappy now thanks to Cyanogen. I'm not talking you-need-to-bencmark-to-see-it speed, I'm talking real-world the-browser-now-launches-super-fast kinda speed. Wished I switched from JF 1.51 earlier. So while upgrading to Cyanogen does have its dangers, I suspect the payoffs more than make up for them. Just check out the list of features that is cooked into his ROM! Worst case scenario - a wipe, small trade off if you ask me.