We captured one error in MW logs, could you have a look ?
plugin_mediawiki_standalone_farm: [b88f5cbc4f54103193fd636e] /mediawiki/w/rest.php/tuleap/maintenance/$PROJECT_NAME/update ErrorException from line 30 of /usr/share/mediawiki-tuleap-flavor/1.35/extensions/TuleapWikiFarm/src/ProcessStep/Maintenance/Update.php: PHP Warning: Could not check compatibility between TuleapWikiFarm\ProcessStep\Maintenance\Update::modifyProcess(TuleapWikiFarm\ProcessStep\Maintenance\Process $process) and TuleapWikiFarm\ProcessStep\Maintenance\MaintenanceScript::modifyProcess(Symfony\Component\Process\Process $process), because class TuleapWikiFarm\ProcessStep\Maintenance\Process is not available #0 /usr/share/mediawiki-tuleap-flavor/1.35/extensions/TuleapWikiFarm/src/ProcessStep/Maintenance/Update.php(5): MWExceptionHandler::handleError()
#1 /usr/share/mediawiki-tuleap-flavor/1.35/vendor/composer/ClassLoader.php(578): include(string)
#2 /usr/share/mediawiki-tuleap-flavor/1.35/vendor/composer/ClassLoader.php(432): Composer\Autoload\ClassLoader::Composer\Autoload\{closure}()
#3 [internal function]: Composer\Autoload\ClassLoader->loadClass()
#4 /usr/share/mediawiki-tuleap-flavor/1.35/vendor/wikimedia/object-factory/src/ObjectFactory/ObjectFactory.php(184): spl_autoload_call()
#5 /usr/share/mediawiki-tuleap-flavor/1.35/vendor/wikimedia/object-factory/src/ObjectFactory/ObjectFactory.php(102): Wikimedia\ObjectFactory\ObjectFactory::getObjectFromSpec()
#6 /usr/share/mediawiki-tuleap-flavor/1.35/extensions/TuleapWikiFarm/src/StepProcess.php(27): Wikimedia\ObjectFactory\ObjectFactory->createObject()
#7 /usr/share/mediawiki-tuleap-flavor/1.35/extensions/TuleapWikiFarm/src/Rest/AuthorizedHandler.php(47): TuleapWikiFarm\StepProcess->process()
#8 /usr/share/mediawiki-tuleap-flavor/1.35/extensions/TuleapWikiFarm/src/Rest/MaintenanceHandler.php(76): TuleapWikiFarm\Rest\AuthorizedHandler->runProcess()
#9 /usr/share/mediawiki-tuleap-flavor/1.35/includes/Rest/Router.php(365): TuleapWikiFarm\Rest\MaintenanceHandler->execute()
#10 /usr/share/mediawiki-tuleap-flavor/1.35/includes/Rest/Router.php(320): MediaWiki\Rest\Router->executeHandler()
#11 /usr/share/mediawiki-tuleap-flavor/1.35/includes/Rest/EntryPoint.php(144): MediaWiki\Rest\Router->execute()
#12 /usr/share/mediawiki-tuleap-flavor/1.35/includes/Rest/EntryPoint.php(111): MediaWiki\Rest\EntryPoint->execute()
#13 /usr/share/mediawiki-tuleap-flavor/1.35/rest.php(31): MediaWiki\Rest\EntryPoint::main()