ERROR: Failed to initialize theme

[kangarooo]

ERROR: Failed to initialize theme

[aniellod]

I had to use the commands:
git config --global url."https://github.com/".insteadOf git://github.com/
git clone --recursive https://github.com/UberGallery/UberGallery.git

This made the themes work properly.

[Atarian6502]

I had the same error. By looking at the code, this error should show when there is no index.php in the themes folder. If you download the code from here as a ZIP file, it has all theme folders empty for some reason. You need to download at least the default theme folder manually (uber-blue)