Despite Bug 383458 Comment #3 I am unable to upload an extension if the install.rdf has compatibility information for Netscape minVer 9.0b1 maxVer 9.0b2. Either turn off version checking for unsupported apps for real or add these version numbers to the version checker.
Philip -- do you have at least one supported app in your install.rdf?
> do you have at least one supported app in your install.rdf? Yes. See: https://addons.mozilla.org/en-US/firefox/addon/433 https://addons.mozilla.org/en-US/firefox/addon/1815
Morgamic added these two versions to the Netscape app, so your bug is FIXED. Have fun! Note: Possible additional changes to the (un)supported apps structure may happen, but are beyond this bug's scope.