Last week I created a new Ionic4 project and wound up having to rip out everything but Android Studio to exorcise version incompatibilities in the build tools. That seemed to fix everything. However, after sending a client a third or fourth debug-signed APK, he reported he couldn't install it. ADB installed it on my tablet just fine, but it couldn't be installed from a webpage or the file system. Since then, some releases have installed, some not.
Investigating with an APK extractor turned up nothing unexpected.
Then I generated a new Ionic project from the sidemenu template, changed the widget ID to a unique name, and changed the homepage a bit. Nothing that should cause an install fail. And it failed!
LogCat showed an install error -22, but nothing more helpful. Turning off the Security Scan option within Play Protect does allow the app to install. If you turn the scan option back on and force a scan, it oddly doesn't complain about the "unsafe" app. Searching Google hasn't turned up any explanation.
Anyone else run into this? Telling clients to turn off security doesn't look great.