Macbook mid-2010 hangs on boot macOS High Sierra

From time to time, my Macbook hangs on boot. I've put the verbose mode startup enabled on each startup so I could figure out what's wrong there.

Here is the line where it is stopping today. You could wait hours, it seems endless. A hard reboot, by keeping your finger on the button, does the job : on next startup the problem does not appear.

Transcript :

ALF, old data swfs_pid_entry < ptr >, updaterules_msg < ptr >, updaterules_state < ptr >

MacOS version is 10.13.6, the last compatible with this Macbook.

Solution 1:

"Waiting for DSMOS" must eventually be followed by "DSMOS has arrived". If it is not, you will never reach loginwindow and Finder. There are a number of reasons why DSMOS isn't completing. Two of the more common ones are:

1. Your filesystem has some corruption that occasionally is within the critical path to the DSMOS mechanism. The immediate next step would be to boot into Recovery mode and run Disk First Aid to check (& repair) your boot volume.
2. The SMC may be getting to a bad state from time to time and failing to read the DSMOS key or pass it to the OS. An SMC reset may fix this.