we have a locally-hosted Enterprise Edition of GitLab at my place of employment (currently at v7.12.00-ee ceb5083). I can create a repository through the GUI without issue.
We've encountered this issue when hosting our gitlab on a "compute engine" from google cloud. The reason for this behaviour was not having a "swap" configured in our machine. Gitlab wasn't able to allocate additional memory.
We decided to scale up our memory instead of creating a swap partition but it's your choice... :)