maintainDB.sh error JdbcDriverLoader.listJdbcDriverJars must not return null

We are trying to backup our Linux teamcity install and migrate to MS SQL using the maintainDB.sh command.

When doing  sudo maintainDB.sh backup -f teamcity.bak

it gives this error

Using source database
        database type: HSQLDB
        database driver: <not specified>
        connection: jdbc:hsqldb:file:/data/teamcity/system/buildserver
        login as: <empty>
Failed: @NotNull method jetbrains/buildServer/serverSide/db/jdbcLoader/JdbcDriverLoader.listJdbcDriverJars must not return null

does any body have an idea as to what is happening.

We are using Redhat 6.0 Ent and Teamcity 7.0