I have read the link you told me followed the steps
1. Open Tools - B4A Sdk manager.
2. Install all recommended items. This will make the switch to AndroidX. You can always go back to the previous SDK.
3. Open Tools - Jetifier.
4. Click on Jetify. It is possible that the jetifier will fail to jetify a few libraries. In most cases you can ignore it as those libraries don't need to be jetified.
5. Clean the project (Ctrl + P)
6. Run your project. The compilation dialog will tell you which SDK was used:
But the error persists
Organizando librerías. (0.00s)
(AndroidX SDK)
Generando el fichero R. Error
AndroidManifest.xml:29: error: Error parsing XML: not well-formed (invalid token)
I don't know if it would be advisable to do a clean installation of androidX, instead of updating SDK to androidX.
and I also use firebasemessaging in my project, I don't know if it has anything to do with the token error, but even if I delete the firebassing lines from the ManifestEditor, the error continues
thx