Thread:Project:Support desk/syntax error: DROP INDEX pl namespace ON `pagelinks`

Hello everyone! I tried updating my mediawiki from 1.6.11 to 1.21.1 and clicked myself through the upgrade routine via "mw-config/index.php". But when updating the database I get an error: The web address is:

 [...] Making pl_namespace, tl_namespace and il_to indices UNIQUE ... An error occurred: Es gab einen Syntaxfehler in der Datenbankabfrage. Die letzte Datenbankabfrage lautete: „DROP INDEX pl_namespace ON `wiki_pagelinks` “ aus der Funktion „DatabaseBase::sourceFile( /var/www/web26/html/felix/exwiki/maintenance/archives/patch-pl-tl-il-unique.sql )“. Die Datenbank meldete den Fehler: „1142: INDEX command denied to user 'web26'@'localhost' for table 'wiki_pagelinks' (localhost)“. Backtrace: Purging caches...done. I could need some help. Does it have something to do with my right as database user? Do I need to contact my homepage provider?
 * 1) 0 /var/www/web26/html/felix/exwiki/includes/db/Database.php(983): DatabaseBase->reportQueryError('INDEX command d...', 1142, 'DROP INDEX pl_n...', 'DatabaseBase::s...', false)
 * 2) 1 /var/www/web26/html/felix/exwiki/includes/db/Database.php(3409): DatabaseBase->query('DROP INDEX pl_n...', 'DatabaseBase::s...')
 * 3) 2 /var/www/web26/html/felix/exwiki/includes/db/Database.php(3322): DatabaseBase->sourceStream(Resource id #259, false, false, 'DatabaseBase::s...', false)
 * 4) 3 /var/www/web26/html/felix/exwiki/includes/installer/DatabaseUpdater.php(639): DatabaseBase->sourceFile('/var/www/web26/...')
 * 5) 4 /var/www/web26/html/felix/exwiki/includes/installer/MysqlUpdater.php(851): DatabaseUpdater->applyPatch('patch-pl-tl-il-...', false, 'Making pl_names...')
 * 6) 5 [internal function]: MysqlUpdater->doUniquePlTlIl
 * 7) 6 /var/www/web26/html/felix/exwiki/includes/installer/DatabaseUpdater.php(435): call_user_func_array(Array, Array)
 * 8) 7 /var/www/web26/html/felix/exwiki/includes/installer/DatabaseUpdater.php(387): DatabaseUpdater->runUpdates(Array, false)
 * 9) 8 /var/www/web26/html/felix/exwiki/includes/installer/DatabaseInstaller.php(274): DatabaseUpdater->doUpdates
 * 10) 9 /var/www/web26/html/felix/exwiki/includes/installer/WebInstallerPage.php(552): DatabaseInstaller->doUpgrade
 * 11) 10 /var/www/web26/html/felix/exwiki/includes/installer/WebInstaller.php(270): WebInstaller_Upgrade->execute
 * 12) 11 /var/www/web26/html/felix/exwiki/mw-config/index.php(65): WebInstaller->execute(Array)
 * 13) 12 /var/www/web26/html/felix/exwiki/mw-config/index.php(33): wfInstallerMain
 * 14) 13 {main}