I narrowed this down to a bug I introduced that affected the uninstall code.EDIT: Also got this when I tried to uninstall v1.2.0.
Can you delete the library/AddOnInstaller off disk and make sure the 1.2.0 contents are uploaded properly?Code:Callback AddOnInstaller_Listener::load_class is invalid (Invalid Method).
Same error. In my case I uninstalled the add-on installer, uploaded the files and XML, "Install from file on server." I've redownloaded the addon, reuploaded to the server, installed from XML uploaded in the browser or sitting on disk in the web root folder and upload folders. Reading the post about files in disk vs memory, I've tried to resubmit it repeatedly, even gave the server a reboot for good measure and repeated it all.
Any other clues for getting around this "edge-case?"
A clean install should work properly, the upgrade path is a bit broken but I've submitted a fix for that.