Yes it was only this warning.
Somehow I solved it, I hope :
I restarted now the phone . Delete the old app . Started the bridge new . Installed the app again and it works.
I sent via firebase console and received.
The question is still what was the problem.
This now the log :
Copying updated assets files (26)
Application_Start
Configuring the default app.
Load Calendar
Application_Active
Application_Inactive
FCMConnected
Application_Active
Application_Inactive
response success
Class (b4i_httpjob) instance released.
Application_Active
Application_Inactive
FCMConnected
Application_Active
FCMConnected
Application_Pushtoken
PushToken: 1
<B4IExceptionWrapper: (null)>
Application_Inactive
Application_Background
Can't endBackgroundTask: no background task exists with identifier 403, or it may have already been ended. Break in UIApplicationEndBackgroundTaskError() to debug.