After updating WordPress and Coblocks from 2.6.0 to 3.1.12, we are no longer able to edit pages that were created using reusable blocks. When clicking on Edit we are getting an error, There has been a critical error on this website. Please check your site admin email inbox for instructions.

In the recovery mode it says that the plugin - Coblocks has caused the error:
Error Details

An error of type E_ERROR was caused in line 47 of the file /data/web/test-fmc-treasury.govnet.qld.gov.au/live/wp-content/plugins/coblocks/includes/block-migrate/class-coblocks-block-migration.php. Error message: Uncaught Error: Class 'DOMDocument' not found in /data/web/test-fmc-treasury.govnet.qld.gov.au/live/wp-content/plugins/coblocks/includes/block-migrate/class-coblocks-block-migration.php:47
Stack trace:
#0 /data/web/test-fmc-treasury.govnet.qld.gov.au/live/wp-content/plugins/coblocks/includes/block-migrate/class-coblocks-block-migration-runner.php(47): CoBlocks_Block_Migration->__construct()
#1 [internal function]: CoBlocks_Block_Migration_Runner->migrate_block()
#2 /data/web/test-fmc-treasury.govnet.qld.gov.au/live/wp-content/plugins/coblocks/includes/block-migrate/loader.php(52): array_map()
#3 /data/web/test-fmc-treasury.govnet.qld.gov.au/live/wp-includes/class-wp-hook.php(326): CoBlocks->{closure}()
#4 /data/web/test-fmc-treasury.govnet.qld.gov.au/live/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters()
#5 /data/web/test-fmc-treasury.govnet.qld.gov.au/live/wp-includes/plugin.php(565): WP_Hook->do_action()
#6 /data/web/test-fmc-treasury.govnet.qld.gov.au/live/wp-includes/class-wp-query.php(4727): d

Downgrading to the previous version temporarily let us edit the pages again.

Would anyone know know to resolve this error with the updated version of Coblocks? Thank you.