You can change the source folder for a Publish post at any time, for example if you've moved your photos to another drive.
What is the source folder?
The source folder is the folder of photos you choose when you start a Publish post. Every photo in it shows in the gallery, ready to add to your post. If you add new photos to the source folder, they show in the gallery too.
What happens if Publish can't find my source folder?
If you move, rename or disconnect your source folder, Publish shows "Source folder [folder name] not found on this device" with a Select Source Folder button. Photos in your post that Publish can't find show a red triangle in their top-right corner.
While the source folder is missing, you can't add new photos from it. If you publish or update your post while a photo is missing, you may see "Your post is missing an image". Click Show Missing Image to find the photo, Remove Image to take it out of your post and carry on publishing, or Cancel.
To fix it, change the source folder to where your photos are now.
How do I change the source folder?
To change the source folder for your Publish post:
Click the folder button in the toolbar.
Click Change Folder Location.
Find the folder in Finder and open it.
Publish changes your post's source folder and adds the photos from the new folder to your gallery.
What happens to my post when I change the source folder?
When you change the source folder, Publish matches the photos in your post to the new folder by file name:
If a photo with the same name is in the new folder, Publish links your post to it.
If a photo isn't in the new folder, it shows a red triangle in its top-right corner.