[3.x]: Craft does not serve custom error templates for 50x error codes when the database is empty or does not exist

[aaronbushnell]

What happened?

Description

When Craft is unable to make a connection to the database or the database contents are emptied/being imported from scratch (causing a 500/503 error) the custom error templates are not rendered.

When using a hosting provider with the ability to restore a database backup (Servd is one such host) the database is emptied and then the backup is imported to take its place.

During this time, even with a 500.twig, 503.twig, offline.twig, and error.twig none of these templates will be shown during this process. Instead you receive (what seems to be) Yii's general error message:

An internal server error occurred.

Steps to reproduce

1. Create an error.twig template
2. Set invalid database credentials
3. Disable dev mode
4. Visit site and see that the error.twig template is not rendered

Expected behavior

The error.twig template should display

Actual behavior

A general "An internal server error occurred." is shown

Craft CMS version

3.7.x (and 4.x)

PHP version

8.0.22

Operating system and version

Darwin 21.6.0

Database type and version

MySQL 5.7.38

Image driver and version

GD 8.0.22

Installed plugins and versions

None

[brandonkelly]

This should be fixed for the next Craft 3 and 4 releases! (#11859)

[aaronbushnell]

Thank you, @brianjhanson and @brandonkelly!

[brandonkelly]

Craft 3.7.54 and 4.2.4 are now tagged with that fix.