After trying to delete a reasonably large repository (~1GB) from the web interface, the connection hangs, and when attempting to access it again Bitbucket gives a 500 Error.
Looking at the log shows the following:
2018-06-27 15:20:49,449 WARN [Navlink Plugin Executor:thread-11] o.h.e.jdbc.spi.SqlExceptionHelper SQL Error: 0, SQLState: null
2018-06-27 15:20:49,450 ERROR [Navlink Plugin Executor:thread-11] o.h.e.jdbc.spi.SqlExceptionHelper bitbucket - Connection is not available, request timed out after 15001ms.
2018-06-27 15:21:04,458 WARN [Navlink Plugin Executor:thread-11] o.h.e.jdbc.spi.SqlExceptionHelper SQL Error: 0, SQLState: null
2018-06-27 15:21:04,458 ERROR [Navlink Plugin Executor:thread-11] o.h.e.jdbc.spi.SqlExceptionHelper bitbucket - Connection is not available, request timed out after 15001ms.
Restarting fixes the hang, but the repository has not been deleted.