Unable to initialize NavBackStackEntry - IllegalStateException: Method addObserver must be called on the main thread [171125856]

Fixed

Bug

Status Update

No update yet.

Description

[Deleted User]

created issue #1

Oct 19, 2020 08:57AM

Component used: Navigation

Version used: 2.2.0, 2.3.0, 2.3.1

Devices/Android versions reproduced on: 10.0, 9.0 - probably not related

Description:

I've updated two dependencies in my project:

androidx.fragment:fragment 1.3.0-alpha06 -> 1.3.0-beta01
androidx.activity.activity 1.1.0 -> 1.2.0-beta01

and now I see that NavController::navigate needs to be called from the main thread. Otherwise NavBackStackEntry throws IllegalStateException when trying to register lifecycle observer.

Stacktrace:

Caused by: java.lang.IllegalStateException: Method addObserver must be called on the main thread
    at androidx.lifecycle.LifecycleRegistry.enforceMainThreadIfNeeded(LifecycleRegistry.java:317)
    at androidx.lifecycle.LifecycleRegistry.addObserver(LifecycleRegistry.java:172)
    at androidx.savedstate.SavedStateRegistryController.performRestore(SavedStateRegistryController.java:61)
    at androidx.navigation.NavBackStackEntry.<init>(NavBackStackEntry.java:84)
    at androidx.navigation.NavBackStackEntry.<init>(NavBackStackEntry.java:69)
    at androidx.navigation.NavController.navigate(NavController.java:970)
    at androidx.navigation.NavController.navigate(NavController.java:867)

There were no changes in documentation so I assume that this behavior is unintended.

Comments

il...@google.com <il...@google.com> #2Oct 19, 2020 08:10PM

What version of Activity are you using? Upgrading your Activity dependency 1.7.2 which also depends on Lifecycle 2.6.1 should resolve this.

[Deleted User] <[Deleted User]> #3Oct 20, 2020 07:19AM

Thanks. I stumbled upon

https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:activity/activity/src/main/java/androidx/activity/ComponentDialog.kt;bpv=1;bpt=0
And see it was fixed in commit 602bac6c67b589d11f8f4d1441a4aec4dca0ee49.
Ill wait to upgrade until after that commit is in the stable release.

ap...@google.com <ap...@google.com> #4Apr 6, 2021 10:13PM

It is stable in the releases I referenced above.

il...@google.com <il...@google.com> #5Apr 6, 2021 10:17PM

Marked as fixed, reassigned to il...@google.com.

Fragment 1.6.1 will update the dependency of Activity to 1.7.2 so you'll get this improvement by default. As mentioned above, you can add a dependency on Activity 1.7.2 right now to fix the issue as a workaround until that release comes out.

ap...@google.com <ap...@google.com> #6Apr 12, 2021 11:58PM

Project: platform/frameworks/support
Branch: androidx-main

commit 00c608a86c44b066198bd8c1dc7e2aef6088d4e1
Author: Ian Lake <ilake@google.com>
Date: Mon Apr 12 14:04:54 2021

Mark popBackStack and navigateUp as @MainThread

In addition to the navigate() and setGraph()
methods updated in

https://android-review.googlesource.com/1665821
the methods for popping the back stack
should also be marked as @MainThread.

Relnote: "Navigation now depends on
[Lifecycle `2.3.1`](/jetpack/androidx/releases/lifecycle#2.3.1)
and now marks all of the methods that update the
`NavBackStackEntry` `Lifecycle`, including `setGraph()`,
`navigate()`, `popBackStack()`, and `navigateUp()`,
as `@MainThread`, aligning Navigation with the main thread
enforcement introduced in Lifecycle `2.3.0`."
Test: existing and updated tests pass
BUG: 171125856

Change-Id: Ib8bedbb3fe384b28c7441cbd57a0751eba307a2b

M navigation/navigation-runtime/api/current.txt
M navigation/navigation-runtime/api/public_plus_experimental_current.txt
M navigation/navigation-runtime/api/restricted_current.txt
M navigation/navigation-runtime/src/main/java/androidx/navigation/NavController.kt

https://android-review.googlesource.com/1673448

Issue 171125856