Solar Lattice

FailureMode

Device firmware defect

ID
fm:firmware-defect
IRI
https://solarlattice.org/kb/fm/firmware-defect
Status
active
Also known as
Firmware bug, unexpected behavior of the inverter software, software bug, communication interrupt after firmware update, Firmware failure, non-existent fault detected, false triggering, Modbus TCP communication loss, Software problem, Firmware programming failure

A firmware defect is a fault in the device software that makes an inverter behave wrongly even when its hardware is fine. It can show up as communication to the monitoring portal dropping after a firmware update and not coming back by itself, which may also trigger configured fall-back modes. Other signs include false trips of fault codes or of the arc fault detector, a software-problem code with no grid feed-in, and firmware versions that do not match between devices or clusters. Check the event log and the installed firmware version to confirm. For Modbus TCP loss, switch the Modbus TCP server parameter off and on to see whether the issue is software-side before you check the cabling. The usual fix is an AC reset and then updating to the firmware version that corrects the bug. If the update file is defective, repeat the update. Never cut DC or AC power or pull the USB stick during an update, because that can damage the software or the device. An internal communication error shown during a firmware update is normal and is not a fault.

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Claims

affects

c1 drafted · lead Inverter

presents_as

c2 drafted · lead Communication loss

In rare cases, after a firmware update the link between an STPxx-50 inverter and the ennexOS portal drops and does not restart by itself.

c3 verified · fact Fallback operation after loss of control or meter signal

The communication loss caused by the firmware issue can trigger fall-back modes, if they are configured.

verified by: review-workflowverified on: 2026-10-24

c4 drafted · lead Spurious fault event

Firmware changelog bugfixes cover false trips of several state codes and false Arc Guard triggering.

c6 drafted · lead Software version mismatch

Extension clusters can run different firmware from the main cluster, or internal devices can carry incompatible firmware versions.

c7 drafted · lead Firmware update failure

Programming firmware from an SD card can fail, and the update file can be defective or damaged.

leads_to

c5 drafted · lead Arc fault nuisance trip

A firmware release reduced false triggering of the Arc Guard.

caused_by

c8 drafted · lead Power supply interruption proposed

Cutting the DC or AC supply, or pulling the USB stick, during an update can damage the software or the device.

review note: support check: partial - u18 says an interrupted power supply can damage the software or device and that the USB stick should not be removed, but it frames this as an update failure and not a firmware defect, and the passages do not list AC or DC cut or USB removal as a cause of a firmware defect.

mitigated_by

c9 verified · fact Firmware update

For example, version 2.2.12.R or higher fixes the STPxx-50 portal communication issue.

verified by: review-workflowverified on: 2026-10-24

c10 drafted · lead Update retry

If the update file is defective, repeat the firmware update.

review note: review: partial - The row supports repeating the update when the update file is defective, but a defective update file is a failed update, not clearly a defect in the device firmware, so the mitigation link to this failure mode is only loosely…

c11 drafted · lead Inverter restart

For a software problem code, an AC reset (switching the circuit breaker off and on) is the first remedy.

detected_by

c12 drafted · lead Inverter event and data log export

Check the event logs and the installed firmware version to confirm whether an update finished and how communication behaved.

review note: support check: partial - u9 asks for the inverter event logs and the installed firmware version, and u22 says to check the events to see whether a firmware update completed, but the passages do not frame this as detecting a firmware defect, and u9 does not tie it to confirming an update.

distinguished_from

c13 drafted · lead Monitoring network configuration fault — told apart by Communication test proposed

Switch the Modbus TCP server parameter off and back on. If communication returns, the problem is limited to Modbus TCP. If it stays down, check the network cabling and RJ45 connections.

review note: support check: partial - u9 describes toggling the Modbus TCP Server parameter to check whether the problem is limited to Modbus TCP and mentions checking network cabling, but it does not compare this with a firmware defect or say that persistent loss means checking the RJ45 connections.

Referenced by

Data