Thread:Project:Support desk/Is there a way to take all the pages in a category and change their NS all at once?/reply (5)

According to Extension:Replace_Text/Version_history, you need version 0.9.4.

I believe this is where you can get it: ReplaceText 0.9.4

Disclaimer: I haven't tested that version, I have no working 1.16 installation right now.