A new feature in iOS 15 is obviously causing problems for apps with a login function. A growing number of users are reporting that they are constantly logging out various apps, so they have to log in again each time the app is started. The first app providers have now published updates that are intended to completely prevent or at least avoid repeated logouts. These include the communication service Twitter and the route planner Komoot. Other programs such as the Telekom app MeinMagenta still show the symptom for some users.
iOS 15 starts apps in the background as a precaution
The constant logout seems to be related to a fundamental innovation of iOS 15: In order to accelerate the app start for the user, the operating system can already “preheat” apps, as Apple announced in advance – Apps should be prepared for this. For this purpose, certain processes of an unused app are started and thus part of the start sequence is practically carried out in the background before the user opens it by hand.
After preheating, the apps remain in a paused state until they are either opened or ejected from the memory by the system. The app is not only preheated after restarting the iPhone, but also regularly during operation – apparently primarily for apps that the system suspects the user will want to open soon.
Access data apparently not available
Preheating increases the likelihood that certain protected data – such as the login data stored in the system-wide keyring – will not yet be available when the app wants to access it, explains a developer. Even if you follow Apple’s documentation exactly, login problems may still occur due to the preheating. Since the operating system decides independently whether and when to preheat certain apps – and this is likely to be different on each iPhone, troubleshooting seems particularly difficult – especially since the bug can sometimes not be reproduced at all.