Hello,
either I'm just stupid or it really doesn't work. I am new to iOS and have been encountering this error for days:
if you have a suggestion what it could be, please describe it to me 
Thank you for your help!
Describe the bug.
The login does not work. As soon as you click on the "log in" button, the app crashes.
Steps to reproduce:
Steps to reproduce the behavior:
Start the app
enter your login details
click on Registration
App crashes
the current development version was used.
App was launched via. xCode combined.
Installation instructions followed.
Tested with iPhone 12 Pro Max
Error code xCode:
metadataFilePath = cachePath
Thread 1: Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value
2021-08-06 05:00:19.254974+0200 Riot[4635:1352111] [MXKViewController] AuthenticationViewController onKeyboardWillShow
2021-08-06 05:00:19.276795+0200 Riot[4635:1352111] [MXKViewController] AuthenticationViewController onKeyboardWillShow
2021-08-06 05:00:25.861740+0200 Riot[4635:1352111] [MXKViewController] AuthenticationViewController onKeyboardWillHide
2021-08-06 05:00:25.870819+0200 Riot[4635:1352111] [MXHTTPClient] #12 - POST _matrix/client/r0/login
2021-08-06 05:00:25.871092+0200 Riot[4635:1352111] [MXBackgroundTask] Start background task #13 - [MXHTTPClient] startBackgroundTask
2021-08-06 05:00:25.871464+0200 Riot[4635:1352111] [MXBackgroundTask] Background task [MXHTTPClient] startBackgroundTask started with app state: active and estimated background time remaining: undetermined
2021-08-06 05:00:26.097604+0200 Riot[4635:1352111] [MXHTTPClient] #12 - POST _matrix/client/r0/login completed in 226ms
2021-08-06 05:00:26.098266+0200 Riot[4635:1352111] [MXHTTPClient] cleanupBackgroundTask
2021-08-06 05:00:26.099040+0200 Riot[4635:1352111] [MXBackgroundTask] Stop background task #13 - [MXHTTPClient] startBackgroundTask after 227.772ms
2021-08-06 05:00:26.100252+0200 Riot[4635:1352111] [MXKAuthenticationVC] Login process succeeded
2021-08-06 05:00:26.105729+0200 Riot[4635:1352111] [MXHTTPClient] #13 - GET _matrix/client/r0/devices/AGOECBCYFY
2021-08-06 05:00:26.106507+0200 Riot[4635:1352111] [MXBackgroundTask] Start background task #14 - [MXHTTPClient] startBackgroundTask
2021-08-06 05:00:26.108010+0200 Riot[4635:1352111] [MXBackgroundTask] Background task [MXHTTPClient] startBackgroundTask started with app state: active and estimated background time remaining: undetermined
2021-08-06 05:00:26.108879+0200 Riot[4635:1352111] [MXKAccountManager] saveAccounts...
2021-08-06 05:00:26.120180+0200 Riot[4635:1352111] [unspecified] container_create_or_lookup_app_group_path_by_app_group_identifier: client is not entitled
2021-08-06 05:00:26.120609+0200 Riot[4635:1352111] [MXKAccountManager] saveAccounts. Done (result: 0) in 12ms
2021-08-06 05:00:26.120947+0200 Riot[4635:1352111] [MXKAccountManager] login (@cryexx:3dns.eu)
2021-08-06 05:00:26.121164+0200 Riot[4635:1352111] [MXKAccountManager] saveAccounts...
2021-08-06 05:00:26.126061+0200 Riot[4635:1352111] [unspecified] container_create_or_lookup_app_group_path_by_app_group_identifier: client is not entitled
2021-08-06 05:00:26.126359+0200 Riot[4635:1352111] [MXKAccountManager] saveAccounts. Done (result: 0) in 5ms
2021-08-06 05:00:26.126527+0200 Riot[4635:1352111] [MXKAccountManager] openSession for @cryexx:3dns.eu account
2021-08-06 05:00:26.127117+0200 Riot[4635:1352111] [MXKAccount] closeSession (0)
2021-08-06 05:00:26.129990+0200 Riot[4635:1352111] [MXSession] setIdentityServer: https://vector.im
2021-08-06 05:00:26.131837+0200 Riot[4635:1352111] [unspecified] container_create_or_lookup_app_group_path_by_app_group_identifier: client is not entitled
MatrixSDK/MXSyncResponseFileStore.swift:59: Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value
2021-08-06 05:00:26.132362+0200 Riot[4635:1352111] MatrixSDK/MXSyncResponseFileStore.swift:59: Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value
(lldb)