I recently stumbled across this bug in SharePoint Online, and would assume that the same bug persists on prem as well.
After having created a new site based on a site template I had created and saved through the UI.
The site itself is a very straight forward one: it is based on the OOTB SharePoint team site, with a few content types associated to the document library, the customer’s logo and changing the theme to the OOTB “Green” theme.
After creating a new site using the new site template I had saved I noticed that for some reason the theme had not changed to the green theme (as per the template). No problem, I simply browsed to the “Change the look” link in the Suite Bar and, to my horror the page was completely blank. I was initially convinced it might be Edge playing up, so went to old school IE – same result, I also tried Chrome and finally Firefox all returned the same blank page.
After some digging around I noticed that the Theme URL field in the Composed Looks gallery was referring to the site name of the original site. I edited the URL of the theme in question (I only needed the one) and checked the “change the look” page again and, presto! it was displaying as expected.
So in short to fix the issue follow these steps;
- Go to Site Setting > Web Designer Galleries > Composed Looks
- Click Edit this list
- Update the Theme URL field from /sites/(original site)_catalogs/theme…. to /sites/(new site)_catalogs/theme….