[Solved] XU4 Upgrade to 8.4.2 hangs


yesterday I started the upgrade to 8.4.2 on my XU4. It hangs at:

 Phase: Installing new DietPi code

[  OK  ] DietPi-Update | Downloading update archive
[  OK  ] DietPi-Update | Unpacking update archive
[  OK  ] DietPi-Update | Removing unused files
[  OK  ] DietPi-Update | Hardening update archive mode
[  OK  ] DietPi-Update | Installing new DietPi scripts
[  OK  ] DietPi-Update | Installing new DietPi system files
[ SUB1 ] DietPi-Set_software > verify_dietpi.txt
[  OK  ] DietPi-Set_software | Downloading current dietpi.txt
[  OK  ] verify_dietpi.txt  | Completed

I killed the process and restarted the upgrade, but it keeps hanging at the same stage.
Any ideas what could be wrong?

Solution: reboot.
But before, I checked what could be the problem. With

ps axf

I saw the subprocess


of dietpi-update. So I tried to run


after killing dietpi-update, and had the same problem.
Since reboot, I can happily sync and dietpi-update finished.


sync syncs data from the filesystem cache onto the disk. If much data was hold in cache and the SD card (?) is slow, this can take a while. Please do not kill (at least not SIGKILL/kill -9) this process but give it a while to finish. I’m not sure whether this can cause filesystem corruption. If one LED is configured to show disk I/O, you should see it flashing as well during sync.

Hi MichaIng,

I know what sync is for. I let it run over night. Still no progress. Then I decided to do a reboot.
The sync subprocesses could not be killed btw…

Hmm that is strange. Does dmesg report any I/O errors of interrupt timeouts?