Make sure that your redis setup is sufficient like described in Hint: Redis setup / configuration for GSE/GVM/OpenVAS.
For productive environments its also strongly suggested use the GVM-9 (stable, initial release 2017-03-07) releases instead of beta releases which might not work as expected yet. Especially as the latest beta release is already half an year old.
Such beta releases should be used only if you want to spent time on your own to debug issues or similar.