App Crashing after iOS upgrade

I have my application installed on my iPhone iOS 5.1.0. I upgraded my device to iOS 5.1.1 and tried running the same installed app. It crashed after i clicked on the app icon. Tough deleting the app and reinstalling it again resolved the issue but my application is live on app store and users are facing issue with iOS upgrade. Asking them to delete and re installing the app is not the solution to the problem which can occour again with the next iOS upgrade.

Queries : 1. How does iOS updates affect the installed app and what cane be the possible reason for the crash.  2. Which are the areas that i should look into for debiugging the issue. 3. Using Keychain access to store acount information.     Any suggestion would be appreciated.

    Incident Identifier: 4DF5A263-B11A-451E-BF05-C447AE33FF61
CrashReporter Key:   7ee0f38606f406732267196b0ef0ac2f4f221477
Hardware Model:      iPhone3,1
Process:         [1105]
Path:            /var/mobile/Applications/86979833-DACF-4D2E-B6E6-714C55038576/Test.app/Test
Identifier:      Test
Version:         ??? (???)
Code Type:       ARM (Native)
Parent Process:  launchd [1]

Date/Time:       2012-05-15 15:47:33.364 -0700
OS Version:      iPhone OS 5.1.1 (9B206)
Report Version:  104

Exception Type:  EXC_CRASH (SIGABRT)
Exception Codes: 0x00000000, 0x00000000
Crashed Thread:  2

Last Exception Backtrace:
(0x376bb88f 0x353c0259 0x376bea9b 0x376bd915 0x37618650 0x89fbd 0x8d90f 0x8d75d 0x87f41 0x37f57c29 0x37eaf6d9 0x37eaf6a3 0x37eaf5c5 0x373537f5 0x373484a5 0x37348599 0x37348599 0x373481a3 0x373480d9 0x3768fad3 0x3768f29f 0x3768e045 0x376114a5 0x3761136d 0x33dd0439 0x313bdcd5 0x29ef 0x29a8)

Thread 0 name:  Dispatch queue: com.apple.main-thread
Thread 0:
0   libsystem_kernel.dylib          0x31872660 0x31861000 + 71264
1   libsystem_c.dylib               0x33f964da 0x33f22000 + 476378
2   libsystem_c.dylib               0x33f683a0 0x33f22000 + 287648
3   libsystem_c.dylib               0x33f682b6 0x33f22000 + 287414
4   libc++abi.dylib                 0x36df5f64 0x36def000 + 28516
5   libc++abi.dylib                 0x36df3346 0x36def000 + 17222
6   libobjc.A.dylib                 0x353c0350 0x353b7000 + 37712
7   libc++abi.dylib                 0x36df33be 0x36def000 + 17342
8   libc++abi.dylib                 0x36df344a 0x36def000 + 17482
9   libc++abi.dylib                 0x36df481e 0x36def000 + 22558
10  libobjc.A.dylib                 0x353c02a2 0x353b7000 + 37538
11  CoreFoundation                  0x37611506 0x37602000 + 62726
12  CoreFoundation                  0x37611366 0x37602000 + 62310
13  GraphicsServices                0x33dd0432 0x33dcc000 + 17458
14  UIKit                           0x313bdcce 0x3138c000 + 203982
15  Test                            0x000029e8 0x1000 + 6632
16  Test                            0x000029a0 0x1000 + 6560

Thread 1 name:  Dispatch queue: com.apple.libdispatch-manager
Thread 1:
0   libsystem_kernel.dylib          0x318623a8 0x31861000 + 5032
1   libdispatch.dylib               0x307e7ea4 0x307db000 + 52900
2   libdispatch.dylib               0x307e7bc2 0x307db000 + 52162

Thread 2 Crashed:
0   libsystem_kernel.dylib          0x31872cd4 0x31861000 + 72916
1   libsystem_c.dylib               0x33f2af36 0x33f22000 + 36662
2   libsystem_c.dylib               0x33f2acc8 0x33f22000 + 36040

Thread 3 name:  WebThread
Thread 3:
0   libsystem_kernel.dylib          0x31862004 0x31861000 + 4100
1   libsystem_kernel.dylib          0x318621fa 0x31861000 + 4602
2   CoreFoundation                  0x3768f3ec 0x37602000 + 578540
3   CoreFoundation                  0x3768e124 0x37602000 + 573732
4   CoreFoundation                  0x3761149e 0x37602000 + 62622
5   CoreFoundation                  0x37611366 0x37602000 + 62310
6   WebCore                         0x32fbac9c 0x32f11000 + 695452
7   libsystem_c.dylib               0x33f3072e 0x33f22000 + 59182
8   libsystem_c.dylib               0x33f305e8 0x33f22000 + 58856

Thread 4:
0   libsystem_kernel.dylib          0x31872cd4 0x31861000 + 72916
1   libsystem_c.dylib               0x33f2af36 0x33f22000 + 36662
2   libsystem_c.dylib               0x33f2acc8 0x33f22000 + 36040

Thread 5 name:  com.apple.NSURLConnectionLoader
Thread 5:
0   libsystem_kernel.dylib          0x31862004 0x31861000 + 4100
1   libsystem_kernel.dylib          0x318621fa 0x31861000 + 4602
2   CoreFoundation                  0x3768f3ec 0x37602000 + 578540
3   CoreFoundation                  0x3768e124 0x37602000 + 573732
4   CoreFoundation                  0x3761149e 0x37602000 + 62622
5   CoreFoundation                  0x37611366 0x37602000 + 62310
6   Foundation                      0x37ea1bb2 0x37e91000 + 68530
7   Foundation                      0x37ea1a7a 0x37e91000 + 68218
8   Foundation                      0x37f3558a 0x37e91000 + 673162
9   libsystem_c.dylib               0x33f3072e 0x33f22000 + 59182
10  libsystem_c.dylib               0x33f305e8 0x33f22000 + 58856

Thread 6 name:  com.apple.CFSocket.private
Thread 6:
0   libsystem_kernel.dylib          0x31872570 0x31861000 + 71024
1   CoreFoundation                  0x3769363a 0x37602000 + 595514
2   libsystem_c.dylib               0x33f3072e 0x33f22000 + 59182
3   libsystem_c.dylib               0x33f305e8 0x33f22000 + 58856

Thread 7:
0   libsystem_kernel.dylib          0x31872cd4 0x31861000 + 72916
1   libsystem_c.dylib               0x33f2af36 0x33f22000 + 36662
2   libsystem_c.dylib               0x33f2acc8 0x33f22000 + 36040

Thread 8:
0   libsystem_kernel.dylib          0x31872cd4 0x31861000 + 72916
1   libsystem_c.dylib               0x33f2af36 0x33f22000 + 36662
2   libsystem_c.dylib               0x33f2acc8 0x33f22000 + 36040

Thread 2 crashed with ARM Thread State:
    r0: 0x00000004    r1: 0x00000000      r2: 0x00000000      r3: 0x00000000
    r4: 0x00980680    r5: 0x0016f428      r6: 0x2ffaf000      r7: 0x2ffaefe0
    r8: 0x3f12ad30    r9: 0x00000001     r10: 0x3f12ad50     r11: 0x00000000
    ip: 0x00000170    sp: 0x2ffaefc0      lr: 0x33f2af3d      pc: 0x31872cd4
  cpsr: 0x40000010