Epic Games Launcher crash on start

Each time I start the Epic Games Launcher it is crashing. It started today and before it was working perfectly. Nothing changed in my system. Does anybody know how to fix it? I reinstalled the launcher but it didn’t help.

Assertion failed: CheckTCharIsHex( Char ) [File:d:\build++portal\sync\engine\source\runtime\core\public\Containers/UnrealString.h] [Line: 2021]

EpicGamesLauncher
EpicGamesLauncher
EpicGamesLauncher
EpicGamesLauncher
EpicGamesLauncher
EpicGamesLauncher
EpicGamesLauncher
EpicGamesLauncher
EpicGamesLauncher
EpicGamesLauncher
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kernel32
ntdll