I have a client using Mosaico beta 3 (WordPress 5.1, Civi 5.7.5). I want to upgrade them to Mosaico beta 4, but they have a number of templates already built and I don't want to lose them when I upgrade. If I uninstall Mosaico beta 3 and install Mosaico beta 4, I will lose them. Anyone know if I can save the templates during the upgrade, and if so, the best way to do so?
@mattwire helped me out. Disable the Mosaico extension, replace the mosaico directory in the extensions directory with the new version, refresh the extensions page in app, enable Mosaico, and run an extensions database upgrade. In this case there were no db upgrades necessary, but there could be depending on the versions.