Fix error “Failed to start DHCP Client Daemon” after upgrade to “Bullseye” on RaspberryPI

Important

This fix can be applied before the reboot after the upgrade from Buster to Bullseye, if you missed it you need a MicroSD card reader and some Linux computer (another RaspberryPI would do) to edit the file.

In the file

/etc/systemd/system/dhcpcd.service.d/wait.conf

there is a wrong path for the dhcpd, it has to be changed.

wrong (from buster):

/usr/lib/dhcpcd5/dhcpcd

correct and new on Bullseye:

/usr/sbin/dhcpcd

So you need to do this before the reboot, otherwise the RaspberryPi will not have a working WIFI or Ethernet connection after the reboot and will not allow you to login from remote by SSH.

If you still have the RaspberryPi running you can use the command from this Stackexchange comment as well.