Un grand merci ! La dernière version de UnrealEngine sur Ubuntu25.04 qui ne voulait rien savoir refonctionne.
suite : mais plante lors du chargement d’un fichier lors de la compilation des shaders (35%), quel que soit le fichier chargé… je télécharge une version précédente du coup (5.5.4).
No way, in this older version the program crash at start 
LoginId:2b218bfe045d414083a9c6d213e8d036-000003e8
Assertion failed: PyWrapperMetaData [File:./../Plugins/Experimental/PythonScriptPlugin/Source/PythonScriptPlugin/Private/PyWrapperBase.cpp] [Line: 128]
PyWrapperMetaData is null for PyType: CameraAssetFactory
libUnrealEditor-PythonScriptPlugin.so!UnknownFunction(0x4f9125)
libUnrealEditor-PythonScriptPlugin.so!UnknownFunction(0x498e5c)
libUnrealEditor-PythonScriptPlugin.so!UnknownFunction(0x573c68)
libUnrealEditor-PythonScriptPlugin.so!UnknownFunction(0x56e83c)
libUnrealEditor-PythonScriptPlugin.so!UnknownFunction(0x57051b)
libUnrealEditor-PythonScriptPlugin.so!UnknownFunction(0x4e293c)
libUnrealEditor-PythonScriptPlugin.so!UnknownFunction(0x530cd0)
libUnrealEditor-Core.so!UnknownFunction(0xc52b37)
libUnrealEditor-Core.so!_ZN14FModuleManager27LoadModuleWithFailureReasonE5FNameR17EModuleLoadResult16ELoadModuleFlags(+0xf63)
libUnrealEditor-Projects.so!_ZN17FModuleDescriptor19LoadModulesForPhaseEN13ELoadingPhase4TypeERK6TArrayIS_22TSizedDefaultAllocatorILi32EEER4TMapI5FName17EModuleLoadResult20FDefaultSetAllocator27TDefaultMapHashableKeyFuncsIS9_SA_Lb0EEE(+0x13c)
libUnrealEditor-Projects.so!UnknownFunction(0x66ea9)
libUnrealEditor-Projects.so!UnknownFunction(0x69c69)
UnrealEditor!UnknownFunction(0x38687)
libUnrealEditor-UnrealEd.so!_Z10EditorInitR11IEngineLoop(+0x208)
UnrealEditor!UnknownFunction(0x42131)
libUnrealEditor-UnixCommonStartup.so!_Z14CommonUnixMainiPPcPFiPKDsEPFvvE(+0x679)
libc.so.6!UnknownFunction(0x2a1c9)
libc.so.6!__libc_start_main(+0x8a)
UnrealEditor!_start(+0x29)