Thanks for taking the time to report this!

Setting https://www.mediawiki.org/wiki/Manual:$wgShowExceptionDetails and pasting more information here is welcome.

That doesn't yield any additional information.

I can't reproduce this bug on an up-to-date MediaWiki installation using SQLite.

I added $wgDebugDBTransactions = true in the configuration.
What do you do to get the error? You have to go to a specific page or do a specific action?

Jackmcbarn: What do you do to get the error? You have to go to a specific page or do a specific action?

Viewing any page causes the error for me. This still happens with latest git, except the error is on line 4096 now (which is still "return (string)$this->mConn;"). This happens with PHP 5.4.22 (with XAMPP 1.8.2) in case that helps.

allex wrote:

I've faced the same issue. The problem starts in debug message:

includes/objectcache/SqlBagOStuff.php:147:

if ( $wgDebugDBTransactions ) {

wfDebug( sprintf( "Connection %s will be used for SqlBagOStuff\n", $db ) );

}

that calls __toString method for $db:

includes/db/Database.php:

public function __toString() {

return (string)$this->mConn;

}

I use MySQL database and in my case $this->mConn is an object of type mysqli that can't be converted to String.

To print type of connection I've changed return expression to $this->getType() but not sure what behaviour was intended.

My config:
MediaWiki 1.22.0 (80d6477)