I create application in b4a version 5.5, which has the signature key used by the debugger (it doesn´'t have a private key), I install the apk on several devices, now I update application using b4a version 9.5, however when reinstalling it, the error "App not install" is displayed , both versions of the application must have the same package name because I am using information from the internal memory that must remain when reinstalling the new version.
do you know if the key is the same? 9.5 may generate a different key than 5.5. did you try to install on a device attached to the ide? were there no unfiltered error messages? android usually spills its guts when there is a problem.
looks like some change was made regarding the debug key at version 6.30. mentioned way down the list. not sure what the change was, but it looks like your 5.5 debug key doesn't match your 9.5 key.