'owner_name' is listed as one of the meta attributes of a Lucene document in eZSolr::metaAttributes (they will end up as "m_<meta-attribute>")

Its value is supposed to be set according to the 'owner' attribute of a contentobject :
line 164

            // Add owner information.
            if ( $owner = $contentObject->attribute( 'owner' ) )
            {
                // Set owner name
                $doc->addField( 'm_owner_name', $owner->name( false, $languageCode ) );
                [...]
            }

The problem lies before, at line 105:

        foreach( eZSolr::metaAttributes() as $attributeName )
        {
            $metaAttributeValues[$attributeName] = $contentObject->attribute( $attributeName );
        }

=> 'owner_name' is not an existing content object attribute, hence the error.

Steps to reproduce

Just basically perform a big (just so it's easy to catch) publishing operation (like a subtree copy in the admin interface) and watch for the error log file.