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Hi everyone I'm working on a successful Wordpress site that also has a forum attached. The forum currently uses YAF forum software, which requires Windows hosting. The site owner wants to switch to Linux hosting. This is not a problem for WP, but it does mean that we'll need to transfer the forum to Xenforo or something similar that runs on Linux. We're OK with the technical side of this, but we're worried about the SEO implications. The URL for every forum post (more than 50,000 of them) is going to change during this transfer. It seems completely impractical to 301 each of those, so should I just 301 the URLs that have inbound links? Also, what is google's algo going to think when we suddenly have ~50,000 404s? Many thanks in advance! J