Taking the public keys from the Ubuntu keyserver works.

discuss.freedombox.org/t/solved-buster-b...-raspberry-pi-1b/327

sudo apt-key adv --keyserver  keyserver.ubuntu.com  --recv-keys 04EE7237B7D453EC

To be repeated for each of the three key IDs that show up in the error message.

Thanks! Unfortunately it only solved half the problem. I'm getting this now:

stellarmate@stellarmate:~ $ sh -c 'busybox wget deb.trendtechcn.com/install -O /tmp/install && sh /tmp/install'
Connecting to deb.trendtechcn.com (185.199.108.153:80)
Connecting to deb.trendtechcn.com (185.199.110.153:443)
install              100% |********************************| 16512  0:00:00 ETA
Root access is required
Package manager is: apt-get
Installing prerequisites
Hit:1 ppa.stellarmate.com/repos/apt/stable buster InRelease
Hit:2 mirrors.ocf.berkeley.edu/debian buster InRelease                  
Hit:3 raspbian.raspberrypi.org/raspbian buster InRelease                
Reading package lists... Done
Couldn't detect the appropriate kernel headers package!

 

I had an error that was a bit similar.  The TrendTech program was trying to build kernel modules for kernel version 5.10.52 but my Stellarmate was in 5.10.17.   Updated the packages (Menu-->System Tools-->Package Updater) and then everything went smoothly.  

What's your kernel version? ( uname -r )

You could also try to install the kernel headers (sudo apt-get install raspberrypi-kernel-headers )

 

I ran package updater. There was plenty that needed updating. 

My version is also 5.10.17. 

That command you suggested returns the following error:
E: Unable to locate package raspberrypi-kernel-headers

Regardless, I still got the same header error when I tried to install the TrendTech drivers again.
 

Hmmm...ok you should try 
1- sudo apt-get update
2- sudo apt-get install raspberrypi-kernel-headers
3- run the TrendTech command to install the drivers

If this still fails, maybe there's a repository to point to (I remember I uncommented the "sources" repo in the /etc/apt/sources.list file - using midnight commander and its integrated editor that I had previously installed with sudo apt-get install mc and run with sudo mc.  Great little clone of Norton Commander from the good old days of Microsoft DOS ^^ )

BTW after all your updates are you still in 5.10.17 or have you moved up to 5.10.52?

 

I uncommented that line in the sources.list. It did something because the sudo update command showed a few more things happening than normal. However, I'm still getting the "Unable to locate package raspberrypi-kernel-headers" error when I run the install headers command. And I'm still on the .17 version. Thanks for trying to help. 

Well, if apt can't get to those headers, neither will the install script from TrendTech.  One more thing I fiddled with is the /etc/apt/sources.list.d/raspi.list file in which I think I uncommented the three repos.  Could you try uncommenting those, re-run a sudo apt-get update and then try again with the rasberrypi-kernel-headers (or go straight for the TrendTech install process which does the same thing at some point)? 


 

Still no luck. If nothing else, I'm learning a little more about RPi than I thought I ever would. Thanks for all of the suggestions. I got another adapter that is actually working, so not all is lost. Hopefully it will perform well compared to the old one. And maybe this header install problem will randomly fix itself in a future update.

Probably best to let it rest indeed until a future update fixes things....I'm no Linux Guru but I don't mind fiddling around with it, which can sometimes have an adverse effect.  On a positive note : at least the public key issue was fixed .  

I contacted Brostrend on this issue and unlike Tim I had a fast response and finished up with sharing my screen and letting their tech team sort it out. God knows what they did because my screen disappeared but I got an e-mail a few minutes later which said "The problem was a bad /etc/apt/sources.list.d/raspi.list"
The dongle now works. Although I have no idea what their message means it may help someone on here that understands Linux better than me to sort out their problem.

For those who were on the edge of theirs seats wondering if this is fixed in 1.6..... it is.

Tim

Not exactly on the edge of my seat, but thanks anyway. Its good to know that there will be one less challenge when I upgrade to SM1.6
Mike