Upgrade to 1.34 produces a Depreciated error on the top of the wiki page.

[danleff]

I manually upgraded my wiki site from version 1.33 to version 1.34 and have been receiving the following message stuck at the top of my wiki. 

Depreciated : Use of $wgLocalInterwiki – use $wgLocalInterwikis instead was deprecated in MediaWiki 1.23.   
 

I am unable to find a solution to this issue and have searched the internet and Media Wiki. Below are the stats for my system. 

Product	Version
MediaWiki	1.34.0
PHP	7.2.24 (cgi-fcgi)
MySQL	5.6.45
ICU

Any assistance is appreciated. 

[Jack Phoenix]

As the error message says, you should use the variable called $wgLocalInterwikis (plural) instead of $wgLocalInterwiki (singular). You will most likely find the offending line of code in your wiki's settings file, LocalSettings.php.

Additionally, if and when you're seeing that (and/or similar notices) on top of your pages, you should verify that your LocalSettings.php file does not contain a line like ini_set( 'display_errors', 1 ); or ini_set( 'display_errors', true ); anywhere. That's what is enabling the displaying of PHP notices, warnings, errors, etc. and it is not recommended to show such messages on a production environment for a variety of reasons.