To TheDJ
Thanks for your help.
Since your answer, I have add somme informations in may first message about the result of "php update.php" with errors and no problem to access the database using phpMyAdmin.
I just add the "MediaWiki debug logging" in LocalSettings.php and also add the "debug" directory with all the right to access but no debug file is created when i run MediaWiki.
But I made a mistake in inserting "$wgShowExceptionDetails = true;" in LocalSettings.php and now I have the following verbose output when running MediaWiki:
MediaWiki internal error.
Original exception: [b397500f6c9871ed9a9fc6b9] /mediawiki/index.php?title=Accueil Wikimedia\Rdbms\DBConnectionError from line 1420 of /volume1/web/mediawiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php: Cannot access the database: Unknown error (localhost:/run/mysqld/mysqld10.sock)
Backtrace:
#0 /volume1/web/mediawiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php(934): Wikimedia\Rdbms\LoadBalancer->reportConnectionError()
#1 /volume1/web/mediawiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php(901): Wikimedia\Rdbms\LoadBalancer->getServerConnection(integer, string, integer)
#2 /volume1/web/mediawiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1046): Wikimedia\Rdbms\LoadBalancer->getConnection(integer, array, string, integer)
#3 /volume1/web/mediawiki/includes/GlobalFunctions.php(2463): Wikimedia\Rdbms\LoadBalancer->getMaintenanceConnectionRef(integer, array, string)
#4 /volume1/web/mediawiki/includes/cache/localisation/LCStoreDB.php(56): wfGetDB(integer)
#5 /volume1/web/mediawiki/includes/cache/localisation/LocalisationCache.php(449): LCStoreDB->get(string, string)
#6 /volume1/web/mediawiki/includes/cache/localisation/LocalisationCache.php(495): LocalisationCache->isExpired(string)
#7 /volume1/web/mediawiki/includes/cache/localisation/LocalisationCache.php(371): LocalisationCache->initLanguage(string)
#8 /volume1/web/mediawiki/includes/cache/localisation/LocalisationCache.php(312): LocalisationCache->loadItem(string, string)
#9 /volume1/web/mediawiki/includes/language/LanguageFallback.php(106): LocalisationCache->getItem(string, string)
#10 /volume1/web/mediawiki/includes/language/LanguageFactory.php(175): MediaWiki\Languages\LanguageFallback->getAll(string)
#11 /volume1/web/mediawiki/includes/language/LanguageFactory.php(121): MediaWiki\Languages\LanguageFactory->newFromCode(string)
#12 /volume1/web/mediawiki/includes/ServiceWiring.php(241): MediaWiki\Languages\LanguageFactory->getLanguage(string)
#13 /volume1/web/mediawiki/vendor/wikimedia/services/src/ServiceContainer.php(447): Wikimedia\Services\ServiceContainer->{closure}(MediaWiki\MediaWikiServices)
#14 /volume1/web/mediawiki/vendor/wikimedia/services/src/ServiceContainer.php(416): Wikimedia\Services\ServiceContainer->createService(string)
#15 /volume1/web/mediawiki/includes/MediaWikiServices.php(623): Wikimedia\Services\ServiceContainer->getService(string)
#16 /volume1/web/mediawiki/includes/Setup.php(700): MediaWiki\MediaWikiServices->getContentLanguage()
#17 /volume1/web/mediawiki/includes/WebStart.php(89): require_once(string)
#18 /volume1/web/mediawiki/index.php(44): require(string)
#19 {main}
Exception caught inside exception handler: [b397500f6c9871ed9a9fc6b9] /mediawiki/index.php?title=Accueil Wikimedia\Rdbms\DBConnectionError from line 1420 of /volume1/web/mediawiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php: Cannot access the database: Unknown error (localhost:/run/mysqld/mysqld10.sock)
Backtrace:
#0 /volume1/web/mediawiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php(934): Wikimedia\Rdbms\LoadBalancer->reportConnectionError()
#1 /volume1/web/mediawiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php(901): Wikimedia\Rdbms\LoadBalancer->getServerConnection(integer, string, integer)
#2 /volume1/web/mediawiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1046): Wikimedia\Rdbms\LoadBalancer->getConnection(integer, array, string, integer)
#3 /volume1/web/mediawiki/includes/GlobalFunctions.php(2463): Wikimedia\Rdbms\LoadBalancer->getMaintenanceConnectionRef(integer, array, string)
#4 /volume1/web/mediawiki/includes/cache/localisation/LCStoreDB.php(56): wfGetDB(integer)
#5 /volume1/web/mediawiki/includes/cache/localisation/LocalisationCache.php(394): LCStoreDB->get(string, string)
#6 /volume1/web/mediawiki/includes/cache/localisation/LocalisationCache.php(312): LocalisationCache->loadItem(string, string)
#7 /volume1/web/mediawiki/includes/language/LanguageFallback.php(106): LocalisationCache->getItem(string, string)
#8 /volume1/web/mediawiki/includes/language/LanguageFactory.php(175): MediaWiki\Languages\LanguageFallback->getAll(string)
#9 /volume1/web/mediawiki/includes/language/LanguageFactory.php(121): MediaWiki\Languages\LanguageFactory->newFromCode(string)
#10 /volume1/web/mediawiki/includes/ServiceWiring.php(241): MediaWiki\Languages\LanguageFactory->getLanguage(string)
#11 /volume1/web/mediawiki/vendor/wikimedia/services/src/ServiceContainer.php(447): Wikimedia\Services\ServiceContainer->{closure}(MediaWiki\MediaWikiServices)
#12 /volume1/web/mediawiki/vendor/wikimedia/services/src/ServiceContainer.php(416): Wikimedia\Services\ServiceContainer->createService(string)
#13 /volume1/web/mediawiki/includes/MediaWikiServices.php(623): Wikimedia\Services\ServiceContainer->getService(string)
#14 /volume1/web/mediawiki/includes/ServiceWiring.php(694): MediaWiki\MediaWikiServices->getContentLanguage()
#15 /volume1/web/mediawiki/vendor/wikimedia/services/src/ServiceContainer.php(447): Wikimedia\Services\ServiceContainer->{closure}(MediaWiki\MediaWikiServices)
#16 /volume1/web/mediawiki/vendor/wikimedia/services/src/ServiceContainer.php(416): Wikimedia\Services\ServiceContainer->createService(string)
#17 /volume1/web/mediawiki/includes/MediaWikiServices.php(925): Wikimedia\Services\ServiceContainer->getService(string)
#18 /volume1/web/mediawiki/includes/exception/MWExceptionRenderer.php(329): MediaWiki\MediaWikiServices->getMessageCache()
#19 /volume1/web/mediawiki/includes/exception/MWExceptionRenderer.php(63): MWExceptionRenderer::reportOutageHTML(Wikimedia\Rdbms\DBConnectionError)
#20 /volume1/web/mediawiki/includes/exception/MWExceptionHandler.php(106): MWExceptionRenderer::output(Wikimedia\Rdbms\DBConnectionError, integer)
#21 /volume1/web/mediawiki/includes/exception/MWExceptionHandler.php(185): MWExceptionHandler::report(Wikimedia\Rdbms\DBConnectionError)
#22 /volume1/web/mediawiki/includes/exception/MWExceptionHandler.php(156): MWExceptionHandler::handleException(Wikimedia\Rdbms\DBConnectionError, string)
#23 [internal function]: MWExceptionHandler::handleUncaughtException(Wikimedia\Rdbms\DBConnectionError)
#24 {main}
Any idea?
I agree with for the "nice" answer from Synology.
I use to be a hardware/software engineer (retired now) but not to much familiar with database and php.
thanks again for your help.