This is not supported. You need to reconfigure from scratch. Usually not hard or time consuming, especially if you use a backup as human reference during the process. If you have stuff that would be more complex or tedious to recreate, let us know what it is and we can help guide you with options.
https://openwrt.org/toh/d-link/dir-835_a1
I would use the D-Link "recovery mode" boot option and use it to flash the most recent OpenWRT factory image. Lowest risk of all and you learn how recovery works for that device, if you do not already know.
This model has NOR flash
flash layout will always change each compile
should upgrade fine with or without keeping settings
if settings don't take, reset button will default back to factory default "without settings"
and yes should also work with factory file via recovery interface
so get both files if you only router
Indeed the 23.05.5 did not complain about bad image.
Could not test the other options from the luci firmware flash interface for I already reset it.
Running 23.05.5 right now.
Although I selected @psherman solution @Lucky1 and @pico had meaningful information @pico That was one of my thoughts and indeed is the lowest risk for bricking @Lucky1 good to know about the NOR flash.
sorry guys i really f... up took the instructions from here and applied to an tp-link archer c7 v2 and all worked fantastic
Unfortunately my D-Link 835 A1 is still in the same situation even with the OpenWrt 23.05.5 I have the same issue 'image check failed. The uploaded image file does not contain a supported format'
This happen also after factory reset.
I am not in the OEM software but openwrt 21.02.0 (after reset) so no 'recovery' interface.
Searching the web did not lend up with meaningful info about TFTP or other means of flashing from outside of a GUI.
Should I force a flash. That is an option on openwrt gui (also from the command line: sysupgrade -F ...)
I am handy can open solder have access to UART console if needed
Well I mixed it up a little myself with the dir-875-A1
but I do have a DIR-825-B2
most still applies
did you try recovery mode ?
Holding down reset until led flashes
setting you ip to 192.168.0.2 255.255.255.0
loading web page at 192.168.0.1
with the DIR-825-B2
I have to use an old browser for the upload to work
I downloaded the old Netscape Navigator at lest for windows 10
and then upload the factory image
@Lucky1 I managed to get it into recovery mode and curently uploading factory image but is unbelievable slow 10kB in a half hour or so. I am monitoring the TCP stream with wireshark.
Only 512Bytes blocks are sent every couple of minutes. It will take days to upload 16MB
I seen it uses Dunkels uIP stack but still so slow...
BTW being so old info is scarse I had to use wayback machine archives. Also I found OEM firmware at a site in australia
They still today have a problem with the Linux TCP stack, so no vm's
try info from this page https://openwrt.org/toh/d-link/dir-825
this is for current routers but may help about linux
failed but I got back into 21.02.1 with all my packages installed in default configuration
at this point I told myself I will try forcing sysupgrade to the latest from the 21.02 series so:
from command line sysupgrade -n -v -F 21.02.7 (could have been from the gui too but ...)
success. from here on from gui flashing next major release first (i.e 22.03.0) then the last (22.03.7)
then 23.05.0.
could not go directly to 23.05.5 (image check failed) so flashed 23.05.4
Appologies:
just realized I might have tried to sysupgrade to 23.05.5 using the factory image so maybe some steps work well but:@Lucky1 Finally done upgrading from 21.02.1 to 23.05.5
Some context:
even 21.02.7 did not pass image check
tried a full reset from the gui but did not wait enough and power cycled