FragmentManager is already executing transactions viewpager2

Question

I am using 4 fragments with view pager 2. And got this error suddenly. The crash does not always appear. I have searched other problems but I could not find any solution about viewpager2.

crash report from mobile could not get the full picture

setUpViewPager() calling this from onStart() of MainActivity

public void setupViewPager() {
        MainActivityViewPager adapter = new MainActivityViewPager(getSupportFragmentManager(), getLifecycle());

        binding.viewpager.setUserInputEnabled(false);

        binding.viewpager.setOffscreenPageLimit(3);

        binding.viewpager.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
            @Override
            public void onPageSelected(int position) {
                if (prevMenuItem != null) {
                    prevMenuItem.setChecked(false);
                } else {
                    binding.bottomNavigation.getMenu().getItem(0).setChecked(false);
                }
                binding.bottomNavigation.getMenu().getItem(position).setChecked(true);
                prevMenuItem = binding.bottomNavigation.getMenu().getItem(position);
            }
        });

        binding.viewpager.setAdapter(adapter);
    }

MainActivityViewPager


public class MainActivityViewPager extends FragmentStateAdapter {


    public MainActivityViewPager(@NonNull FragmentManager fragmentManager, @NonNull Lifecycle lifecycle) {
        super(fragmentManager, lifecycle);
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
        switch (position) {
            case 0:
                return new HomeFragment();
            case 1:
                return new ProgressFragment();
            case 2:
                return new MoreFragment();
            case 3:
                return new ProfileFragment();
        }
        return null;
    }

    @Override
    public int getItemCount() {
        return 4;
    }

Can anyone suggest me a solution? This is currently happening in a production app and I have got red alert on my head. Thank you people

"And got this error suddenly." - which error? post stacktrace — snachmsm, Dec 02 '20 at 09:16
I could not get the stack trace from android studio. but I managed to have a report from a mobile where the app crashed. please check the link in the problem — Niaz Sagor, Dec 02 '20 at 09:22

score 13 · Accepted Answer · answered Dec 02 '20 at 09:37

13

basing on log your ViewPager is placed inside (nested?) Fragment, so you should use getChildFragmentManager instead of getSupportFragmentManager

answered Dec 02 '20 at 09:37

snachmsm

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no viewpager is not nested. I have **MainActivity**, inside it I have **viewpager2** along with bottom navigation. – Niaz Sagor Dec 02 '20 at 10:38
I was looking at wrong direction. Thank you for your response – Niaz Sagor Dec 02 '20 at 19:58
@NiazSagor did you find a solution? I'm having a similar issue and I'm a bit lost – moyo May 04 '21 at 14:28
@moyo yes the above answer is working correctly – Niaz Sagor May 05 '21 at 18:56

FragmentManager is already executing transactions viewpager2

1 Answers1