Update

[Milog]

I have an A51 which was updated on Monday and now I can't use any of my mobile apps such as mobile banking, outlook, some game won't launch etc. These worked perfectly well before this update. 

I have tried shutting down and restarting etc which made no difference. Is there something I need to be doing ie changing setting or permissions to allow these apps to open.

[antikythera]

Read the pinned notice about updating all apps via Google Play and follow the instructions to do so and restart your phone after

[Broads]

Update your system Web view in the play store and all apps turn device on and off will work was due to a buggy update

[AndrewL]

@Milog: Further to the advice offered above, please follow the link below to find a helpful, step by step guide to resolve your issue. I hope this helps. 

https://www.samsung.com/uk/support/mobile-devices/why-are-some-android-apps-crashing/