it's since one year that i release unsigned apk with Fabric without problems. My work colleague has configured a new Mac for releasing sometimes the same app (always unsigned apk). If he release the apk, with Beta (Fabric) i can't install the apk.
We have the same version of Android Studio 3.4.1 and Fabric (for Android Studio) 4.3.0 .
thanks for your help.
The solution is to share the same debug.keystore