My app sometimes crashes when in background and shows the following crash log:

Nov  7 12:33:31 iPad backboardd[29] <Warning>: MyApp[3096] has active assertions beyond permitted time: 
    {(
        <BKProcessAssertion: 0x14680c60> identifier: Called by MyApp, from -[AppDelegate applicationDidEnterBackground:] process: MyApp[3096] permittedBackgroundDuration: 180.000000 reason: finishTask owner pid:3096 preventSuspend  preventIdleSleep  preventSuspendOnSleep 
    )}

Looking through other questions I found out that the crash message indicates that I didn't end a task properly, so when its time expired the OS ended it and crashed my app.

So I added some NSLogs:

- (void)applicationDidEnterBackground:(UIApplication *)application
{       
    [self saveContext];
    [Settings setCallLock:YES];

    [self saveStuff];

    if ([self isBackgroundTaskNeeded]) 
    {

        UIApplication*  app = [UIApplication sharedApplication];

        bgTask = [app beginBackgroundTaskWithExpirationHandler:^{

            [self pauseDownloads];

            NSLog(@"Debug - Ending background task %d",bgTask);
            [app endBackgroundTask:bgTask];
            NSLog(@"Debug -  Background task %d ended",bgTask);
            bgTask = UIBackgroundTaskInvalid;


        }];
        NSLog(@"Debug - Starting background task %d",bgTask);
        [self initBackground];

    }

}

and found out that the task was called twice when it crashed:

Nov  7 12:30:02 iPad MyApp[3096] <Warning>: Debug - Starting background task 7
Nov  7 12:30:30 iPad MyApp[3096] <Warning>: Debug - Starting background task 8
Nov  7 12:33:26 iPad MyApp[3096] <Warning>: Debug - Ending background task 8
Nov  7 12:33:26 iPad MyApp[3096] <Warning>: Debug -  Background task 8 ended
Nov  7 12:33:26 iPad MyApp[3096] <Warning>: Debug - Ending background task 0
Nov  7 12:33:26 iPad MyApp[3096] <Warning>: Debug -  Background task 0 ended

I wasn't able to tell when the double call happens and why. So question is why is the task being called twice and is there a way to avoid it?

Edit:

- (void) pauseDownloads
{
    for (AFDownloadRequestOperation *operation in self.operationQueue.operations)
    {
        if(![operation isPaused])
        {
            [operation pause];
        }
    }
}