Publisher giving Error 400 code?

This one worked for me!

Disabling the "Experiences that download online content" within "Connected experiences" worked for me, Thank you! When I replace a picture now, it shows a message with a button to work offline and when I click this, I can select the new image.

I do not recommend performing the Repair online except as a last resort. This was the first method I tried and it did not fix the HTTP Error 400 code. Not only does it take a while to redownload Office and install, it also asked me to re-enter my office key for product activation. So make sure to have your Office Key ready if you intend trying the Repair Online method, unless its linked to your Microsoft or corporate account. Clearing the webview2 folder did not fix the issue either, but again thanks for the suggestion.

YES! That worked ... but only after I unchecked ALL CONNECTED EXPERIENCE as well.

And once it worked in this document, I checked on all the others I had and it had unchecked those in them as well.

Thank you!

I was experiencing the same issue. I do a lot of mailings for real estate agents and find it time-consuming not being able to swap the photos out anymore. After reading everyone's responses, I just tried to update Office 365, with my last resort being to talk with tech support. The update itself did nothing (File -> Account -> Update Options (on the right side of screen) -> Update Now). However, on one of my templates, I clicked "Compress Pictures" ONCE on ONE template/file and now "Change Picture" is working on every single template/file I've created. I'd say it's worth a shot since it worked for me. I have no clue if the update had anything to do with that, but these were just the steps I took. But it's working for me now :) Hooray!

I know that this doesnt fix the issue, but if I drug and dropped the photo into Microsoft Publisher (rather than adding the photo through the program) then the error didn't occur. Not really a solution, but a alright work-around!