Some users are encountering a Fatal Error while trying to activate the plugin. As I mentioned in my previous blog post, that is because PHP is unable to load the php_sockets extension PemFTP needs. Even though this really is the reason why some users are encountering that error, they actually should not be. If there wasn’t a bug in the code that decides which implementation it should choose, it should have fallen back to the pure PHP implementation whenever php_sockets extension is not available. To reproduce this bug, you need to run PHP in Safe Mode and disable the php_sockets installation. Since the bug was in the library that comes with the WordPress by default and none of my testing environments had such configuration, it was hard to spot the cause at the first place. Luckily, I managed to find the bug and opened a ticket to bring this to the attention of Core Developers of WordPress. And today, it is marked for commit which means that WordPress 3.4 will have this bug fixed.

I want to thank everyone who brought this error to my attention on behalf of all WordPress users because you helped fixing a bug that had been there since WordPress 2.5. You guys rock!