Troubleshooting

The upload fails with an error

Confirm you are uploading the template .xml file and not the ZIP archive or a documentation file.
Re-extract the original package. A file that was edited and saved by a word processor can contain invalid characters.
Try a different browser or a private window.

Widgets disappeared after installing

Restoring a theme can remove widgets that have no matching section in the new template. Open Layout and re-add them. If you saved a backup, compare it with the new layout.

The site does not look like the demo

A demo contains sample posts, labels and widgets. Create the same labels and widget setup described in the template notes.

Mobile layout looks wrong

Check that you have not disabled the mobile view in Blogger settings, and clear your browser cache. Test in a private window.

Custom code stopped working

Restoring a theme replaces the theme file, including code you added. Re-apply your changes after each update.

Going back

Use Restore with the backup you downloaded before installing.