[Plugin: WordPress Importer] Fatal error with 0.4 and WP 3.0.5

That’s quite strange. Those line numbers look to be the start and end of the function, which would seem to suggest that wordpress-importer.php is being loaded more than once. The earlier code is surrounded by an if exists, that is why it’s late in the code.

Do you have the experience or a coder friend that could help you comment out the rest of the file and dump the call stack instead?

As lloydbudd says that fatal error indicates that the importer plugin has been loaded twice. This used to occur as a bug if the script died during the plugin activation hook, but after the plugin had been added to the active_plugins option. Firstly this was fixed in 3.0.2/3.1 and second the importer doesn’t do anything on the activation hook.

Currently the only other way I can think of this happening if there is another plugin hooked into activated_plugin (or a similar action) which is causing the script to end after the importer has been added to the active_plugins array.

You could try deactivating all other plugins and then activate the importer to see if there’s a difference. Or manual activation by adding to the active_plugins option and checking for a fatal error (as this one requires database manipulation of a serialized field I wouldn’t recommend trying it on a production site or if you’re not confident enough).