Sideloading the Storyteller APK over the Play Store build fails: package "contradicts" the installed one

I wanted to install a newer Android build from the GitLab releases page (2.7.3) over the 2.6.1 build I originally got from the Play Store. The installer prompts to update, then fails with an error saying the package conflicts with / contradicts the currently installed package.

Resolution: This is Android's signature check, not a bug in the build: the APKs published on GitLab Releases are signed with a different certificate than the Play Store build, and Android refuses to upgrade an installed app in place unless the signing certificate matches. Your options are to uninstall the Play Store version first and then install the GitLab APK (this wipes app data, including books you downloaded to the device, so re-download them from the server afterwards), or wait for the Play Store release, which is the same code but often lags by days because of review times. If you plan to stay on the GitLab-signed builds, install one that way once and then use Obtainium pointed at the GitLab Releases page to track updates — all subsequent updates will match the certificate. Do not uninstall while you have no working connection to your server, since you will not be able to restore the downloaded books.