Issue Description

When I upgrade V86 firmware to V87, there is an error like "Rom Invalid" and the upgrade fails.

Conclusion

The older V86 firmware has a different firmware verification process when using the WebUI to upgrade, which causes this issue when directly upgrading to V87 via WebUI.

To solve this

This problem does not exist when using the Auto Provision method to upgrade V86 to V87. So you can try using Auto Provision to upgrade firmware.
If you need to upgrade via the web user interface, please try to upgrade to the interim firmware below first:

After that, you would be able to upgrade to V87 via the web user interface.
For further support, please submit ticket at ticket.yealink.com.