Pihole -up ends in error unable to complete

Expected Behaviour:
Running pihole -up performs an upgrade
Running Raspian 10, on a raspberry pi.

  • Pi-hole [v5.12.2]
  • Web Interface [v5.15.1]

Actual Behaviour:

FTL does not upgrade and does not run.
Upgrade script ends in message 'Unable to complete update, please contact Pi-hole Support'
Pihole is not running since.
Updating and upgrading OS does not fix the issue. Pihole -r and fresh install did not fix it either.

Debug Token:

https://tricorder.pi-hole.net/WdhbfVLO/

Your debug log shows an error when starting FTL:

Sep 21 08:32:37 raspberrypi pihole-FTL[3690]: /usr/bin/pihole-FTL: /lib/arm-linux-gnueabihf/libc.so.6: version `GLIBC_2.28' not found (required by /usr/bin/pihole-FTL)
Sep 21 08:32:38 raspberrypi systemd[1]: pihole-FTL.service: Control process exited, code=exited status=1

This means your system is using an outdated GLIBC library.
Usually Debian 10 have the right one. You need to update it (or find out why it is using the outdated one).

pi@ph5b:~ $ strings /lib/arm-linux-gnueabihf/libc.so.6 | grep GLIBC
GLIBC_2.4
GLIBC_2.5
GLIBC_2.6
GLIBC_2.7
GLIBC_2.8
GLIBC_2.9
GLIBC_2.10
GLIBC_2.11
GLIBC_2.12
GLIBC_2.13
GLIBC_2.14
GLIBC_2.15
GLIBC_2.16
GLIBC_2.17
GLIBC_2.18
GLIBC_2.22
GLIBC_2.23
GLIBC_2.24
GLIBC_2.25
GLIBC_2.26
GLIBC_2.27
GLIBC_2.28
GLIBC_2.29
GLIBC_2.30

Thanks, fixed it.