I have an Android 2.1 phone (an Acer Liquid A1) which recently started throwing an error during the calendar sync. It kept showing a "force close" error.
I got my laptop setup to connect to the phone using the Acer Liquid Tool (USB drivers) and the Malez recovery software, which includes the ADB debugging software.
After connecting the phone via USB and running ADB logcat, I was able to get the following error from the phone when I sync'd the calendar:
W/dalvikvm( 823): threadid=15: thread exiting with uncaught exception (group=0x2aac6160)
E/AndroidRuntime( 823): Uncaught handler: thread SyncThread exiting due to uncaught exception
E/AndroidRuntime( 823): java.lang.NullPointerException
E/AndroidRuntime( 823): at com.android.providers.calendar.CalendarSyncAdapter.fetchCalendarsFromServer(CalendarSyncAdapter.java:1622)
E/AndroidRuntime( 823): at com.android.providers.calendar.CalendarSyncAdapter.getServerDiffs(CalendarSyncAdapter.java:1223)
E/AndroidRuntime( 823): at android.content.TempProviderSyncAdapter$SyncThread.runSyncLoop(TempProviderSyncAdapter.java:367)
E/AndroidRuntime( 823): at android.content.TempProviderSyncAdapter$SyncThread.sync(TempProviderSyncAdapter.java:287)
E/AndroidRuntime( 823): at android.content.TempProviderSyncAdapter$SyncThread.run(TempProviderSyncAdapter.java:218)
After an awful lot of Googling, I still had no answer.
It looks like the 2.1 version of Android supplied by Acer, has a flaw that prevents it working properly with some new Google calendar feature.
I don't know what the problem is.
Instead, to solve the problem, I flashed the ROM back to stock Acer Android 1.6.
The calendar then worked again properly, however, I had lost an awful lot of good functionality (Facebook integration, better Gmail & Android Market app versions etc etc).
So I tried another option. I used a link on the Modaco forums for a hacked version of the Android 2.2 OS which was for the new Acer LiquidE (same phone hardware, but with 512MB of RAM instead of 256MB).
Someone has posted a version which had been enabled to run on my 256MB Acer Liquid (genius).
I flashed the 2.2 ROM onto the phone and the calendar now works again.
Despite the problem, this highlighted an area of short sightedness. When/if the online Google apps are no longer supported or work on older Android versions, this will make the phones that use the older Android versions effectively worthless. Who wants an Android phone with no cloud capability?