Victron Multi VE.Bus Err 11 relay test fault. Where do I look?

The short answer

Update firmware, check AC-in wiring and earth, test AC-out loads, and check neutral-out and input L/N.

Plain explanation

From the Victron manual for the MultiPlus-II: Update FW. Check wiring/earth on AC in. The rest of the checklist is below; work through it in order. Installer only: DC and AC work on a live PV system is dangerous, so owners should note the code and call their installer. Grid limits depend on your country, so check your national code and grid operator rules.

Steps from the source

Update FW
Check wiring/earth on AC in
Disconnect L/N ACout to test loads
Neutral-out no external link
L/N input inverted

Source

Victron VE.Bus error codes (official docs), Err 11www.victronenergy.com ↗

Where installers ask this

General guidance based on the manufacturer's manual or the named source. Always follow the current manual for your exact model and your national code. DC and AC electrical work is for qualified installers only. Not affiliated with or endorsed by any brand named; trademarks belong to their owners.