Wemos CH34x driver crash

Yesterday i downloaded the CH34x_Install_V1.4 00.09.08.pkg from Wemos and installed the driver. After asking me to reboot – what i did – my system was not booting anymore. :/ I have a Mac Book Pro 2012 with macOS High Sierra 10.13.3 installed.

After a while seeing just the Apple and asking myself, if there ist really no movement in the bar, i started to figure out what was wrong.

As it was quite hard to find the right commands and explanations and as it seems a lot of people had or have the same or a similar issue, i will write about it here.

Thanks to Säschi for helping although it was late.

How to remove a driver (here: CH34x ) from a Mac, using the single user mode.

Start up your Mac in Single-User Mode by holding down Command-S while starting the Mac. Continue until you see white text on the screen.
we want to find the .kext files of the driver and than delete them… as we installed the driver with a given .pkg file (CH34x_Install_V1.4 00.09.08.pkg) we have to see find the installed .pkg file at our mac at first. BUT as the installed .pkg file has a different name we have to find the right installed .pkg file at first using the command $ pkgutil –pkgs=“part of the name what we are looking for“ :
pkgutil --pkgs=*ch34xinstall*
(just that you know: pkgutil --pkgs shows every installed .pkg packages…)
as a result you will get something like:
com.wch.ch34xinstall.mykextdir.pkg
juhu – we found it – this is the name of the installed CH34x_Install_V1.4 00.09.08.pkg
now we want to see where is the content of this pkg installed:
pkgutil --files com.wch.ch34xinstall.mykextdir.pkg
as a result you will get something like:
usbserial.kext
usbserial.kext/contents
usbserial.kext/contents/Info.plist
usbserial.kext/contents/MacOS
usbserial.kext/contents/MacOS/usbserial
usbserial.kext/contents/Resources
usbserial.kext/contents/Resources/en.lproj
usbserial.kext/contents/Resources/en.lproj/InfoPlist.strings
usbserial.kext/contents/_CodeSignature
usbserial.kext/contents/_CodeSignature/CodeResources
We have the fucking kext: its usbserial.kext!
But where is this fucking kext on the Mac:
find / -name "usbserial"
It should be somewhere in the Library/Extensions/ or System/Library/Extentions but as the the delete Command rm is powerful and dangerous we want to be really sure…. so hav a look what the find command gave us back:
Something like:
/Library/Extensions/usbserial.kext/… bla bla bla
this finde: /Library/StagedExtensions/Library/Extensions/usbserial.kext/… bla bla bla is something in the temp – maybe because the installer wanted us to restart our mac after installing the CH34x_Install_V1.4 00.09.08.pkg
ok – perfect – finally we delete it:
! caution the rm -rf command will delete everything forever… be absolutely sure what you were doing and what you want to delete:
rm -rf /Library/Extensions/usbserial.kext
now we want to see if everything is gone:
find / -name "usbserial"
now you maybe just finde this:
/Library/StagedExtensions/Library/Extensions/usbserial.kext/Contents/MacOS/usbserial
This probably will be gone after a restart.
IF you have problems to delete the file – see TIPP 1 and TIPP 2
restart your mac – it occurs that while restarting, at the point of loading the usbserial.kext the mac start again – but this time successfully 🙂

Tipp 1: If you can’t delete the kext files – you have to disable the SIP (System Integrity Protection)

Start your Mac in recovery mode with holding Command + R while booting.

Utilities -> Terminal

with: csrutil status you see the status of SIP

with: csrutil disable you disable SIP

restart your mac in Single-User mode and try the steps above again…

after deleting the kext and a successful start of your mac you have to enter the recovery mode again and enable SIP using: csrutil enable

Tipp 2: If you still can’t delete the kext files and the sudo rm -rf command shows: Read-only file system – you have to mount the disk with writing rights using the command: mount -uw /