原文来自:Modify Firefox 1.5 to work with all extensions

firefox的插件安装时要判断版本，所以nightly或者新版本安装后经常没办法装插件。有人就发现了这个办法。简单地说，就是在 about:config 中新建 app.extensions.version，值为 1.0 ，装好之后改回去也可以用。判断版本应该是为了稳定性考虑，这样做可能会导致一些问题，谁知道呢…

For all of those who just downloaded Firefox 1.5 and can’t get your extensions to work. This is a simple modification of Firefox’s configuration to trick the extensions to work. No need to manually edit the extensions to get them to work. Currently all the extensions I use work except the bookmark sync extension that I so dearly want to.

1. At the location bar, enter: about:config. This will show you a list of Firefox internal preferences.

2. Right-click on the list, select New > String

Enter “app.extensions.version” (without quotes) for the preference name.

3. Then, enter “1.0” (without quotes) as the value for app.extensions.version.

4. Restart Firefox 1.5, then enable those disabled Firefox extensions.

5. Restart Firefox 1.5 again to active the extensions. Done.

Personally I think this is the best solution because you can always go back and delete the string later rather then fiddling with the extensions.

[UPDATE]

if you change 1.0 back to 1.5 Spoofstick [and potentially others] will continue to work and can also look for updates.

相关资料：

让插件兼容 firefox 2.0