[wp-trac] [WordPress Trac] #51988: Call to undefined function mysql_connect()

[WordPress Trac]

#51988: Call to undefined function mysql_connect()
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 Reporter:  bgin          |       Owner:  (none)
     Type:  defect (bug)  |      Status:  closed
 Priority:  normal        |   Milestone:
Component:  Database      |     Version:  5.6
 Severity:  normal        |  Resolution:  invalid
 Keywords:                |     Focuses:
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Comment (by desrosj):

 From @ipajen on #52001:

 > I was using PHP 7.4 (where the mysql_connect() was removed already and
 everything worked fine) until before upgrading to PHP 8. No changes has
 been made except upgrading to PHP 8. So the question is why does it want
 to use mysql_connect instead of correct mysqli. Got 3 word press
 installltions on same hosting and all has the same problem, one of is very
 newly installed.

 As of the release of PHP 8, the `@` operator will no longer suppress
 errors fatal errors.

 Looking at [https://core.trac.wordpress.org/browser/tags/5.6/src/wp-
 includes/wp-db.php#L1684 the code in WordPress], unless `WP_DEBUG` mode is
 enabled, the `@` operator preceded the `mysql_connect()` call. In previous
 versions of PHP, it's likely that this just failed silently, and just
 happened to work on accident.

 As noted above, if `mysqli_connect()` is present on the server running
 WordPress, it will always be used unless `WP_USE_EXT_MYSQL` is defined as
 `true`.

 The only ways to encounter this issue would be a PHP install with `mysqli`
 missing or improperly configured, or the `WP_USE_EXT_MYSQL` being set to
 `true`. I would search in the `mu-plugins` directory, check your active
 plugins/`wp-config.php` file, or reach out to your hosting provider for
 more help. It's possible the hosting environment has incompatibilities
 with PHP 8 at the system level.

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Ticket URL: <https://core.trac.wordpress.org/ticket/51988#comment:6>
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