After upgrading from 2.6.0 CE to 23.01 Backup Does not work

[apt]

After upgrading from 2.6.0 CE to 23.01 attempt to manually download a XML configuration file fails with a PHP error:

PHP ERROR: Type: 1, File: /usr/local/pfSense/include/www/backup.inc, Line: 108, Message: Uncaught Error: Call to undefined function gzdeflate() in /usr/local/pfSense/include/www/backup.inc:108
Stack trace:
#0 /usr/local/pfSense/include/www/backup.inc(219): ssh_keys_xml()
#1 /usr/local/www/diag_backup.php(63): execPost(Array, Array)
#2 {main}

Corresponding crash report:

Crash report begins.  Anonymous machine information:

amd64
14.0-CURRENT
FreeBSD 14.0-CURRENT #0 plus-RELENG_23_01-n256037-6e914874a5e: Fri Feb 10 20:30:29 UTC 2023     root@freebsd:/var/jenkins/workspace/pfSense-Plus-snapshots-23_01-main/obj/amd64/VDZvZksF/var/jenkins/workspace/pfSense-Plus-snapshots-23_01-main/sources/FreeBS

Crash report details:

PHP Errors:
[06-Apr-2023 17:41:53 Canada/Eastern] PHP Fatal error:  Uncaught Error: Call to undefined function gzdeflate() in /usr/local/pfSense/include/www/backup.inc:108
Stack trace:
#0 /usr/local/pfSense/include/www/backup.inc(219): ssh_keys_xml()
#1 /usr/local/www/diag_backup.php(63): execPost(Array, Array)
#2 {main}
  thrown in /usr/local/pfSense/include/www/backup.inc on line 108
[06-Apr-2023 17:46:31 Canada/Eastern] PHP Fatal error:  Uncaught Error: Call to undefined function gzdeflate() in /usr/local/pfSense/include/www/backup.inc:108
Stack trace:
#0 /usr/local/pfSense/include/www/backup.inc(219): ssh_keys_xml()
#1 /usr/local/www/diag_backup.php(63): execPost(Array, Array)
#2 {main}
  thrown in /usr/local/pfSense/include/www/backup.inc on line 108
[09-Apr-2023 16:28:57 Canada/Eastern] PHP Fatal error:  Uncaught Error: Call to undefined function gzdeflate() in /usr/local/pfSense/include/www/backup.inc:108
Stack trace:
#0 /usr/local/pfSense/include/www/backup.inc(219): ssh_keys_xml()
#1 /usr/local/www/diag_backup.php(63): execPost(Array, Array)
#2 {main}
  thrown in /usr/local/pfSense/include/www/backup.inc on line 108

[rcoleman-netgate]

@apt Have you installed the system patches package? If not do so and run all the updates and reboot your system.
https://docs.netgate.com/pfsense/en/latest/development/system-patches.html

[JimBob Indiana]

@apt Restore failed for me as well. Had to manually reconfigure 2.7.

[stephenw10]

Exactly the same php error?

Undefined function errors like that are more often issues with the upgrade itself.