Troubleshooting for the Android app
If something seems to be going wrong on the app, the first step to try is to close the app completely and then re-open it. To close the app, tap on your device's app manager and swipe to close the Trello app.
If the problem continues after closing and re-opening the app, there are a few things you can try to fix the problem: clearing the cache, logging out of the app and back in, or reinstalling the app.
WARNING: These actions will clear any offline changes you've made to your boards that haven't been synced yet, so make sure to check for unsent changes before proceeding further.
Check for unsent changes first!
If you've made changes to your boards while offline, the troubleshooting steps described further down will prevent these changes from being synced. Fortunately, there are a few different ways to check to see if you have any unsent changes. You can also check for sync indicators (circular arrows) on boards in the home screen and on cards, like in the screenshot below:
Finally, you can view the Sync Queue in the settings menu. To get to "Settings", select the hamburger icon in the upper left corner. This will open the navigation drawer where you'll see "Settings" at the bottom.
What to do if you have unsent changes
If you see any of these indications that you have unsent changes, clearing the cache, logging out and back in, or reinstalling the app will cause you to lose these changes. To prevent this, the best course of action is to get back on a network so that the changes will sync.
If that doesn't work at first, try closing the app completely by tapping on the home screen and swiping up on Trello, and then reopening Trello. If the changes still don't sync after that, check to make sure that the network is working by opening a webpage in your browser.
If you're not able to get on a network, or if the changes don't send for some reason, you can export a list of the changes so that you can redo them later if they're lost. To do this, open the app and go to the Account tab. From there, open the Sync Queue. Tap on the share button to send yourself a text description of the changes.
Troubleshooting after checking for unsent changes
After you've confirmed that you don't have any unsent changes, or after you've exported the Sync Queue as a backup, you can safely continue with the troubleshooting steps below.
Clearing the cache
Sometimes, cached data in the Android app will cause your Android device to be out of sync with the web interface.
To clear that, open your phone's Settings app, then go to 'Apps' and scroll down until you see the Trello app listed. Tap on Trello, and then tap on 'Storage'. Finally, tap on "Clear Cache".
Logging out of the app and back in
If clearing the cache doesn’t help, you may want to try logging out of the app and back in. To log out, first open the Trello app, tap the hamburger menu button in the upper left, and select "Settings" at the bottom of the navigation drawer.
Once you’ve logged out, select “Log In” to sign in to Trello again.
Reinstalling the app
If the problem persists, you can also reinstall the app. Delete the app from the device, and reinstall it from the Google Play Store. You’ll need to log in again.
Reaching out to Trello Support in-app
While on Trello home, click on the menu icon in the top left and tap on 'Settings' then 'Report a Bug'. A draft email will be formulated with some baseline device information to help us streamline the debug process. In the report email, please include exact steps you’re taking in the app, and what you actually see (screenshots are always appreciated!) vs. what you expect to see.
Here is a great example of a bug report: http://help.trello.com/article/709-reporting-trello-bugs