Upgrading from RT-AC56U_376.49?

[A&DnPA]

I've been "sleeping" for a few years and just woke up and realized I should upgrade the firmware to the latest release. Any suggestions on what is the best practice to upgrade from a old firmware?

 

[A&DnPA]

Thanks.
Tried going directly to 380.65 and it failed. Tried going to 378.55 and it worked and from there onto 380.65_4. Factory to default after final flash and manual reconfig all the settings. So far so good!