Unable to upgrade from 386.x to 386.x

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Senior Member
I figured rather than pollute the 386.1 thread I’d create a new one and see if anyone had any ideas.

I had been running Merlin 384.19 on my RT-AC88U and upgraded to 386.1. I got a couple of lockups so I decided to do a factory reset, clear NVRAM and JFFS and set things up from scratch.

Things were well until I tried to upgrade to 386.1_2, which failed because the router said the firmware was invalid, so it failed whatever check ASUS on a firmware upgrade. It did the same thing when I tried to upgrade to the 386.2 alpha. It succeeded when I re-flashed to 386.1, which was already installed.

I tried all the following with the same result:
  1. Removing USB thumb drive and rebooting.
  2. Factory reset through the UI, clearing NVRAM and JFFS and skipping setup and going to upgrade page.
I then decided to try flash the official ASUS firmware from https://www.asus.com/us/Networking/RT-AC88U/HelpDesk_BIOS/ which is currently That also failed.

At this point I decided to use the Rescue Tool and flash which worked. I then tried flashing 386.1_2 which failed, but so did trying to flash 386.1_0, which had previously worked. I also tried factory resetting and that still failed.

On a whim, I flashed 384.19 which worked! I was then able to flash 386.1_2 successfully.

As such it seems like the only way to flash a new version of 386.x on my RT-AC88U is to downgrade to 384.19 first, but I have no idea why that would be.

I don‘t use QOS or any of the Trend stuff. I also don’t use any advanced features of the router or have any custom scripts or anything else installed.

I normally have at least 378 MB memory free.

Any idea what’s wrong?
Last edited:

noah way

Regular Contributor
68U / 384.19 froze on boot after 386.1 update. Had to reset twice to get it working. Now it's running smooth and fast. Looks like the connection increased > 50 Mbps.


Senior Member
68U / 384.19 froze on boot after 386.1 update. Had to reset twice to get it working. Now it's running smooth and fast. Looks like the connection increased > 50 Mbps.
Doesn’t seem related to my issue as I have no issue upgrading from 384 to 386. The problem I have is 386 to 386.


Regular Contributor
Adding to this thread, yesterday I had a similar problem with 'Invalid Firmware Upload 'upgrading an AC68U from 386.1 to 386.1_2. I double checked the firmware download was correct and the checksum and tried a different browser - tried both Vivaldi (Chrome) and Firefox; I was using a laptop running Archlinux. I decided to put the task aside, in the hope that maybe somebody would add some information to this thread.

Today I tried to upgrade again using a laptop running Windows 10 & Firefox, it went without a hitch.


Senior Member
The computer I was using was a Windows 10 laptop. I tried both Firefox and Edge.

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