We have setup TYPO3 behind a TRAEFIK Reverse Proxy. Yesterday everything looks good, but today our Backend is empty. In the Browser Console we found

“Mixed Content: The page at ” was loaded over HTTPS, but
requested an insecure script ”. This request has been blocked;
the content must be served over HTTPS.”

And after that the following errors:

‘TypeError: Failed to fetch dynamically imported module:
https://xxx.xxx.de/typo3/sysext/backend/Resources/Public/JavaScript/live-search/result-types/page-result-type.js?bust=c8eb9eafbb5af2f5c1b1dbbd651572846060258b’

Why TYPO3 is trying to load a Script with an insecure URL?

Our Website seems to be good. But Login into Backend ends up with the left Menu und a white Screen:

    <?php
return [
    'BE' => [
        'debug' => false,
        'disable_exec_function' => 0,
        'installToolPassword' => '*****',
        'lockSSL' => 0,
        'loginRateLimit' => 3,
        'loginRateLimitInterval' => '5 minutes',
        'loginRateLimitIpExcludeList' => '*****',
        'passwordHashing' => [
            'className' => 'TYPO3\CMS\Core\Crypto\PasswordHashing\Argon2idPasswordHash',
            'options' => [],
        ],
        'sessionTimeout' => 28800,
        'showRefreshLoginPopup' => true,
        'versionNumberInFilename' => '0',
        'warning_email_addr' => '*****',
        'warning_mode' => 0,
    ],
    'DB' => [
        'Connections' => [
            'Default' => [
                'charset' => 'utf8',
                'dbname' => '*****',
                'driver' => 'mysqli',
                'host' => 'database',
                'password' => '*****',
                'port' => 3306,
                'user' => '*****',
            ],
        ],
        'extTablesDefinitionScript' => 'extTables.php',
    ],
    'EXT' => [],
    'EXTENSIONS' => [
        'backend' => [
            'backendFavicon' => '',
            'backendLogo' => '',
            'loginBackgroundImage' => '',
            'loginFootnote' => '© 2024 ******',
            'loginHighlightColor' => '',
            'loginLogo' => 'EXT:******/Resources/Public/Images/mbFavicon.svg',
            'loginLogoAlt' => '******',
        ],
        'extensionmanager' => [
            'automaticInstallation' => '0',
            'offlineMode' => '0',
        ],
        'flux' => [
            'autoload' => '1',
            'debugMode' => '0',
            'doktypes' => '0,1,4',
            'flexFormToIrre' => '0',
            'handleErrors' => '0',
            'pageIntegration' => '1',
            'plugAndPlay' => '0',
            'plugAndPlayDirectory' => 'design',
        ],
        'indexed_search' => [
            'catdoc' => '/usr/bin/',
            'debugMode' => '0',
            'deleteFromIndexAfterEditing' => '1',
            'disableFrontendIndexing' => '0',
            'enableMetaphoneSearch' => '1',
            'flagBitMask' => '192',
            'fullTextDataLength' => '0',
            'ignoreExtensions' => '',
            'indexExternalURLs' => '0',
            'maxAge' => '0',
            'maxExternalFiles' => '5',
            'minAge' => '24',
            'pdf_mode' => '20',
            'pdftools' => '/usr/bin/',
            'ppthtml' => '/usr/bin/',
            'unrtf' => '/usr/bin/',
            'unzip' => '/usr/bin/',
            'useMysqlFulltext' => '0',
            'xlhtml' => '/usr/bin/',
        ],
        'powermail' => [
            'disableBackendModule' => '0',
            'disableIpLog' => '1',
            'disableMarketingInformation' => '0',
            'disablePluginInformation' => '0',
            'disablePluginInformationMailPreview' => '0',
            'enableCaching' => '0',
            'replaceIrreWithElementBrowser' => '0',
        ],
        'save_and_close' => [
            'saveAndClose' => '1',
            'saveAndView' => '1',
        ],
        'scheduler' => [
            'maxLifetime' => '1440',
        ],
        'static_info_tables' => [
            'enableManager' => '0',
        ],
        'vhs' => [
            'disableAssetHandling' => '0',
        ],
        'videos' => [
            'controls' => '1',
        ],
        'ws_t3bootstrap' => [
            'tidy' => '0',
        ],
    ],
    'FE' => [
        'compressionLevel' => 0,
        'debug' => false,
        'loginRateLimit' => 3,
        'loginRateLimitInterval' => '5 minutes',
        'loginRateLimitIpExcludeList' => '******',
        'passwordHashing' => [
            'className' => 'TYPO3\CMS\Core\Crypto\PasswordHashing\Argon2idPasswordHash',
            'options' => [],
        ],
    ],
    'GFX' => [
        'gdlib_png' => 1,
        'jpg_quality' => '86',
        'processor' => 'GraphicsMagick',
        'processor_allowTemporaryMasksAsPng' => false,
        'processor_colorspace' => 'RGB',
        'processor_effects' => false,
        'processor_enabled' => true,
        'processor_path' => '/usr/bin/',
    ],
    'INSTALL' => [],
    'LOG' => [
        'TYPO3' => [
            'CMS' => [
                'deprecations' => [
                    'writerConfiguration' => [
                        'notice' => [
                            'TYPO3CMSCoreLogWriterFileWriter' => [
                                'disabled' => true,
                            ],
                        ],
                    ],
                ],
            ],
        ],
    ],
    'MAIL' => [
        'defaultMailFromAddress' => 'no-reply@******',
        'defaultMailFromName' => '******',
        'transport' => 'smtp',
        'transport_sendmail_command' => '/usr/sbin/sendmail -t -i ',
        'transport_smtp_encrypt' => false,
        'transport_smtp_password' => '',
        'transport_smtp_server' => '******',
        'transport_smtp_username' => '',
    ],
    'SYS' => [
        'UTF8filesystem' => true,
        'belogErrorReporting' => 0,
        'caching' => [
            'cacheConfigurations' => [
                'autoloader' => [
                    'backend' => 'TYPO3\CMS\Core\Cache\Backend\SimpleFileBackend',
                    'frontend' => 'TYPO3\CMS\Core\Cache\Frontend\PhpFrontend',
                    'groups' => [
                        'system',
                    ],
                    'options' => [
                        'defaultLifetime' => 0,
                    ],
                ],
                'extbase_object' => [
                    'backend' => 'TYPO3\CMS\Core\Cache\Backend\ApcuBackend',
                    'frontend' => 'TYPO3\CMS\Core\Cache\Frontend\VariableFrontend',
                    'groups' => [
                        'system',
                    ],
                    'options' => [
                        'defaultLifetime' => 0,
                    ],
                ],
                'hash' => [
                    'backend' => 'TYPO3\CMS\Core\Cache\Backend\Typo3DatabaseBackend',
                ],
                'imagesizes' => [
                    'backend' => 'TYPO3\CMS\Core\Cache\Backend\Typo3DatabaseBackend',
                    'options' => [
                        'compression' => true,
                    ],
                ],
                'pages' => [
                    'backend' => 'TYPO3\CMS\Core\Cache\Backend\Typo3DatabaseBackend',
                    'options' => [
                        'compression' => true,
                    ],
                ],
                'rootline' => [
                    'backend' => 'TYPO3\CMS\Core\Cache\Backend\Typo3DatabaseBackend',
                    'options' => [
                        'compression' => true,
                    ],
                ],
            ],
        ],
        'ddmmyy' => 'd.m.Y',
        'devIPmask' => '*',
        'displayErrors' => 0,
        'encryptionKey' => '******',
        'exceptionalErrors' => 12290,
        'features' => [
            'security.backend.htmlSanitizeRte' => true,
            'security.usePasswordPolicyForFrontendUsers' => true,
        ],
        'phpTimeZone' => 'Europe/Berlin',
        'reverseProxyHeaderMultiValue' => 'first',
        'reverseProxyIP' => '172.18.0.*,172.20.0.*',
        'reverseProxySSL' => '*',
        'sitename' => '******',
        'systemLocale' => 'de_DE.utf8',
        'systemMaintainers' => [
            5,
        ],
        'trustedHostsPattern' => '.*',
    ],
];