In older TubePress installations, you might see the following error message where you galleries once were:
YouTube responded to TubePress with an HTTP 410 - No longer available
This message means that are using an outdated version of TubePress that relies on a service from YouTube that was shutdown in 2015. This blog post offers further details.
The solution is simple: simply upgrade to the latest version of TubePress. We also recommend that you look at this forum post, which lists pitfalls to watch out for when upgrading from an old version of TubePress.