Two model numbers are not enough information to describe a working pairing. The firmware versions on both sides are part of it, and almost nobody tracks that.
Closed-loop communication is an implementation, and implementations get revised. A battery BMS update can change how a value is reported. An inverter update can add a protocol profile, rename one, or change which profile is selected by a stored setting. Either side can therefore break a link that worked for a year, with no wiring change and no visible fault.
Why this is worse than an ordinary bug
The failure is usually quiet. The system keeps inverting, the loads keep running, and what stops is the negotiation. The inverter falls back to voltage-based charging, and the pack goes back to protecting itself by disconnecting rather than by asking for less current.
Nothing on the front panel necessarily says so. The first symptom is often a charge profile that behaves oddly, or a BMS disconnect under a load that used to be fine. People chase that as a battery fault for weeks.
What to do before you update
Write down what is working while it is working: firmware version on the inverter, firmware version on the BMS, the protocol profile selected, and the date. This takes two minutes and it is the only record that will exist, because no manufacturer publishes a compatibility matrix across versions.
Then update one side at a time, and give it a full charge and discharge cycle before touching the other. If closed loop drops out, you know which change caused it. Updating both together removes that information permanently.
Check whether your equipment allows a rollback before you need one. Some units do not, and knowing that in advance changes how cautious you want to be.
How to tell closed loop is actually live
Do not rely on a status light. Look for the pack reporting a real state of charge to the inverter, and a charge current that tapers on the BMS request rather than on a voltage threshold. If the inverter is showing state of charge estimated from voltage, the link is not doing its job, whatever the settings screen claims.
Why this site does not check firmware
Because the data does not exist to check against. This site compares published manufacturer figures, and version-to-version compatibility is not published by anyone. Recording that gap honestly is more useful than implying a model-level match covers it.
If you have a manufacturer document that states a minimum firmware version for a specific pairing, that is genuinely rare and worth sharing: info@solarspecdb.com
Status: describes a documented failure mode reported repeatedly by builders. No manufacturer publishes a firmware compatibility matrix, so no version-specific claim is made here.