PHP Notice: Undefined variable: collate

[Hax]

Since the $collate is not defined.

If the none of the conditions are met the $collate variable is never set. This issue could also affect $charset. I am not getting a php notice for $charset just yet only for $collate.

https://core.trac.wordpress.org/browser/trunk/src/wp-includes/wp-db.php#L752

[kraftbj]

There's no default option for $charset or $collate in that section if the defined( 'DB_COLLATE') check fails. I believe the expectation is that should be set in wp-config.php (and is by default).

[Hax]

yes, but the variables should still be set, either to Null or empty string. The notice is that the variables are not set.

[SergeyBiryukov]

Thanks for the report, we're already tracking this issue in #37683.