The following workaround should get you into the game and back to enjoying all of its features:
- If it is open, close Terraria completely
- Turn on your phone's Airplane Mode so that no data or wi-fi is enabled
- Start Terraria (you will likely still get the same error message, but the game should load to the main menu now)
- Once you're at the main menu/title screen, turn Airplane Mode off
- Now you can login, access your cloud saves, and get back online