How do I force reinstallation of an apk with different signature on rooted Android? Normally I can reinstall (reserving application data) APK only when it's signature matches the previous one.

How do I force upgrading of apk (from distribution to self-compiler version, for example) without uninstallation using root access?

Workaround is backup application's data + uninstall + install + restore data, but that is inconvenient and notifies other applications about [un]installation which is not wanted.
You can use an app called 'Lucky Patcher' witch contains many system tweaks, (root and busybox are required) then follow the following steps:


Go to 'Toolbox' tab in the buttom.
Select 'Patch to Android'.
Check 'Disable signature verification in the package manager'.
Press 'Apply' and wait for your phone to reboot.


and that's it. 'Lucky Patcher' also has an Xposed module to do the same task if Xposed is already installed in your system.