–the MM still runs with the dri3 error for now. Perhaps it wont make any difference. Just one of those glitches. I thought it was why i could not boot. but it was (of course) an error i introduced in the config.js which i couldnt find and had to back track to the default and try again. Sure it is a little frustrating - but it is also how I learn ; by making mistakes.

–Now back to MM - I do not currently have a specific module issue. I want to have mostly basic stuff - like clock, Google calendar, weather - at least to start. I dont think i will need much else, i hope

I appreciate the help
Thanks everyone

I am getting the same error on a fresh sd card on a rpi 3B with buster 32bit installed. It has manually installed MagicMirror, node, etc., no extra modules, just the config sample copied to be config.js.
…
[2092:0905/201909.167187:ERROR:viz_main_impl.cc(186)] Exiting GPU process due to errors during initialization
[2132:0905/201909.521340:ERROR:gpu_memory_buffer_support_x11.cc(44)] dri3 extension not supported.
[2106:0905/201909.609131:ERROR:command_buffer_proxy_impl.cc(126)] ContextResult::kTransientFailure: Failed to send GpuControl.CreateCommandBuffer.
…

I did more digging and I am not sure if this is the right solution for a Raspberry Pi 3B running Buster
I followed the instructions on this page [https://www.raspberryconnect.com/projects/35-games/142-trying-out-opengl-on-raspberry-pi-3] and the viz_main and gpu memory buffer and other stuff disappeared. I’m now playing with the different settings in the raspi-config and going to up the split memory. I tried first with settings it to 128 , half of what they recommended, cause I’m just contrary my mama says. And MagicMirror does seem to run more smoothly than with the default buster install. BUT the pi is much worse at multi tasking now. I can’t have very many chromium windows going at once. So, i’m going to play with the video setttings more. I know I won’t be running chromium when the mirror is running. But if I put a lot of modules into the magic mirror… it would stress the pi too.

Anyway, perhaps this info will help you.

Note: on the last buster install, the raspi-config advanced options and performance options are a little different location in the menu than described in this article.

Kelly

at least whatever was hanging up MM , it is working now
and i am banging my head against modules and minor CSS to add background

It can be frustrating but it is fun to search for possible solutions and experiment and learn

I am sure there are lots of options that i cant locate.
The hunting for the answers before asking is part of my learning challenge.

• i will work on it some more, search threads before making a new question. I have to be sure it isnt something i just mis-optioned, typo… need to look at it tomorrow with fresh eyes

–if you think i should switch to 32-bit Raspian i will do that as well

the Raspian desktop is slightly outside (larger than) the monitor screen, but the MM is displayed well inside the borders so if i get it all set on this monitor i will stick to this one.

that error is a video driver problem.

you ‘might’ be able to fix this by disabling use of the gpu.

edit package.json and change

"start": "DISPLAY=\"${DISPLAY:=:0}\" ./node_modules/.bin/electron js/electron.js",

to

"start": "DISPLAY=\"${DISPLAY:=:0}\" ./node_modules/.bin/electron --disable-gpu  js/electron.js",