use my userid at gmail

add

export ELECTRON_DISABLE_GPU=1

in the script that starts mm
just before the npm start line

MM is running on a Pi with it’s own screen.
But in the meantime I got it working again. I found this threat with had similar errors as I had when running ‘startx’.

After I removed this driver MM started again:
sudo mv /usr/share/X11/xorg.conf.d/99-fbturbo.conf ~
startx

But I do still have the following errors in the error-log:

[16183:1013/103255.149031:ERROR:viz_main_impl.cc(186)] Exiting GPU process due to errors during initialization
[16220:1013/103256.721936:ERROR:gpu_memory_buffer_support_x11.cc(44)] dri3 extension not supported.
[16188:1013/103256.801401:ERROR:command_buffer_proxy_impl.cc(126)] ContextResult::kTransientFailure: Failed to send GpuControl.CreateCommandBuffer.

pi 27931 5155 0 22:18 pts/0 00:00:00 grep --color=auto -i x11

ok, try this

ps -ef  | grep Xorg 

is this a server machine?, or does it have a display? where MM is shown?

I have done a manual update of MM and pi when the problems started.
I have also tried to run your installation script but the problem is still there. I have also tried to update node.js and npm to the latest versions.

These are requested outputs:

$ node -v
v18.10.0

$ npm -v
8.19.2

$ lsb_release -a
No LSB modules are available.
Distributor ID: Raspbian
Description: Raspbian GNU/Linux 10 (buster)
Release: 10
Codename: buster

$ uname -a
Linux raspberrypi 5.15.56-v7+ #1575 SMP Fri Jul 22 20:28:11 BST 2022 armv7l GNU/Linux

$ ps -ef | grep -i x11
pi 27931 5155 0 22:18 pts/0 00:00:00 grep --color=auto -i x11

node -v
npm -v
lsb_release -a
uname -a
ps -ef | grep -i x11

how did u upgrade? manual or my script?
if my script can u send me the installers/upgrade.log

use my userid at gmail. ( file is too big to post here)

note that you must be running the graphical desktop for MM full mode to execute …

server only mode without desktop is ok
npm run server

then u would access from some other system

magicmirror@2.21.0 start
DISPLAY=“${DISPLAY:=:0}” ./node_modules/.bin/electron js/electron.js

[12.10.2022 13:36.16.036] [LOG] Starting MagicMirror: v2.21.0
[12.10.2022 13:36.16.052] [LOG] Loading config …
[12.10.2022 13:36.16.068] [LOG] Loading module helpers …
[12.10.2022 13:36.16.074] [LOG] No helper found for module: alert.
[12.10.2022 13:36.16.114] [LOG] Initializing new module helper …
[12.10.2022 13:36.16.116] [LOG] Module helper loaded: updatenotification
[12.10.2022 13:36.16.119] [LOG] No helper found for module: clock.
[12.10.2022 13:36.16.660] [LOG] Initializing new module helper …
[12.10.2022 13:36.16.665] [LOG] Module helper loaded: calendar
[12.10.2022 13:36.16.669] [LOG] No helper found for module: compliments.
[12.10.2022 13:36.16.671] [LOG] No helper found for module: weather.
[12.10.2022 13:36.16.720] [LOG] Initializing new module helper …
[12.10.2022 13:36.16.721] [LOG] Module helper loaded: newsfeed
[12.10.2022 13:36.16.723] [LOG] All module helpers loaded.
[12.10.2022 13:36.16.973] [LOG] Starting server on port 8080 …
[12.10.2022 13:36.17.004] [LOG] Server started …
[12.10.2022 13:36.17.006] [LOG] Connecting socket for: updatenotification
[12.10.2022 13:36.17.008] [LOG] Starting module helper: updatenotification
[12.10.2022 13:36.17.010] [LOG] Connecting socket for: calendar
[12.10.2022 13:36.17.012] [LOG] Starting node helper for: calendar
[12.10.2022 13:36.17.014] [LOG] Connecting socket for: newsfeed
[12.10.2022 13:36.17.018] [LOG] Starting node helper for: newsfeed
[12.10.2022 13:36.17.019] [LOG] Sockets connected & modules started …
[24680:1012/133617.027945:ERROR:ozone_platform_x11.cc(247)] Missing X server or $DISPLAY
[24680:1012/133617.028297:ERROR:env.cc(226)] The platform failed to initialize. Exiting.
/home/pi/MagicMirror/node_modules/electron/dist/electron exited with signal SIGSEGV

first 5 or 6 lines

==> MagicMirror-error.log <==
[24318:1012/112446.727714:ERROR:env.cc(226)] The platform failed to initialize. Exiting.
/home/pi/MagicMirror/node_modules/electron/dist/electron exited with signal SIGSEGV
[24496:1012/112454.856543:ERROR:ozone_platform_x11.cc(247)] Missing X server or $DISPLAY
[24496:1012/112454.856766:ERROR:env.cc(226)] The platform failed to initialize. Exiting.
/home/pi/MagicMirror/node_modules/electron/dist/electron exited with signal SIGSEGV
[24565:1012/112510.603377:ERROR:ozone_platform_x11.cc(247)] Missing X server or $DISPLAY
[24565:1012/112510.603597:ERROR:env.cc(226)] The platform failed to initialize. Exiting.
/home/pi/MagicMirror/node_modules/electron/dist/electron exited with signal SIGSEGV
[24624:1012/112526.200613:ERROR:ozone_platform_x11.cc(247)] Missing X server or $DISPLAY
[24624:1012/112526.200835:ERROR:env.cc(226)] The platform failed to initialize. Exiting.

Did you find a solution?

must be full desktop mode