site broken after upgrade to php 7.3

[dsanchez]

After upgrading PHP from 7.1.x to 7.3.x the message

Sorry, SMF was unable to connect to the database. This may be caused by the server being busy. Please try again later.

is being shown.

Apache error logs show this:

[Sun Sep 18 11:46:24.441747 2022] [php7:error] [pid 26746] [client 216.244.66.196:38210] PHP Fatal error:  Uncaught Error: Call to undefined function mysqli_error() in /var/www/html/smf/Sources/Errors.php:456\nStack trace:\n#0 /var/www/html/smf/Sources/Subs-Db-mysql.php(76): display_db_error()\n#1 /var/www/html/smf/Sources/Load.php(3655): smf_db_initiate('localhost', 'db', 'user', 'password', 'smf_', Array)\n#2 /var/www/html/smf/index.php(94): loadDatabase()\n#3 {main}\n  thrown in /var/www/html/smf/Sources/Errors.php on line 456
[Sun Sep 18 11:46:25.895841 2022] [php7:error] [pid 26745] [client 185.191.171.40:46594] PHP Fatal error:  Uncaught Error: Call to undefined function mysqli_error() in /var/www/html/smf/Sources/Errors.php:456\nStack trace:\n#0 /var/www/html/smf/Sources/Subs-Db-mysql.php(76): display_db_error()\n#1 /var/www/html/smf/Sources/Load.php(3655): smf_db_initiate('localhost', 'db', 'user', 'password', 'smf_', Array)\n#2 /var/www/html/smf/index.php(94): loadDatabase()\n#3 {main}\n  thrown in /var/www/html/smf/Sources/Errors.php on line 456

please advise. thank you!

[dsanchez]

some things needed to be installed after the php upgrade:

sudo apt install php7.3-mysql

also

sudo apt-get install php7.3-mbstring

of course later we need to restart apache

sudo /etc/init.d/apache2 restart

that solved the issue.