There is security software like Avast and Kaspersky and BitDefender and ESET that intercept secure connections and send their own certificate.

If you can't inspect the certificate via "I Understand the Risks" then try this:

Open the "Add Security Exception" window by pasting this chrome URL in the Firefox location/address bar and check the certificate:

• chrome://pippki/content/exceptionDialog.xul

In the location field of this window type or paste the URL of the website.

• retrieve the certificate via the "Get certificate" button
• click the "View..." button to inspect the certificate in the Certificate Viewer

You can inspect details like the issuer and the certificate chain in the Details tab of the Certificate Viewer. Check who is the issuer of the certificate. If necessary then you can attach a screenshot that shows the certificate viewer.

Thank you very much for your answer, cor-el.

No, I haven't got the opportunity of "I understand the risk". And when I tried what you suggested for https://www.google.se for example, I got the window you see on the screenshot.

hi, please go into the programs section of your system control panel and uninstal nvidia forceware network access manager in case you have that present.

Connectivity or crashing issues after Firefox 43 update

Hi philipp,

thank you very much for your answer and for the link. I didn't find it earlier when I looked for solution. Unfortunately, I don't have this programm installed (see screenshot).

ok thanks, that was just a wild guess since you've said it is just happening since a few days.

could you go to the firefox menu ≡ > help ? > troubleshooting information, copy the contents of that page and paste them here into a reply on the forum? this might give us a clue what is going on...

Yes, here you go:

Allgemeine Informationen

Name: Firefox Version: 43.0.2 Build-ID: 20151221130713 Update-Kanal: release User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:43.0) Gecko/20100101 Firefox/43.0 Fenster mit mehreren Prozessen: 0/1 (Standard: false) Abgesicherter Modus: false

Absturzberichte der letzten 3 Tage

Alle Absturzberichte

Erweiterungen

Name: Adblock Plus Version: 2.7 Aktiviert: true ID: {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d}

Name: Check4Change Version: 1.9.7 Aktiviert: true ID: check4change-owner@mozdev.org

Name: Dict.cc Translation Version: 3.5.3 Aktiviert: true ID: searchdictcc@roughael

Name: Proxy-Listen.de - Proxyswitcher Version: 1.0.4.5.1-signed Aktiviert: true ID: admin@proxy-listen.de

Name: Swap Proxy Version: 1.2.1-signed Aktiviert: true ID: swapproxy@mahendra.com

Name: Video DownloadHelper Version: 5.4.2 Aktiviert: true ID: {b9db16a4-6edc-47ec-a1f4-b86292ed211d}

Grafik

Asynchrones Wischen und Zoomen: nichts Direct2D aktiviert: Wurde auf Grund Ihrer Grafiktreiberversion blockiert. DirectWrite aktiviert: false (6.2.9200.17568) Gerätekennung: 0x0046 Gerätekennung (GPU #2): 0x0a70 GPU #2 aktiv: false GPU-beschleunigte Fenster: 1/1 Direct3D 11 (OMTC) H264-Hardware-Dekodierung unterstützt: Yes Herstellerkennung: 0x8086 Herstellerkennung (GPU #2): 0x10de Karten-Beschreibung: Intel(R) HD Graphics Karten-Beschreibung (GPU #2): NVIDIA GeForce 310M Karten-RAM: Unknown Karten-RAM (GPU #2): 1024 Karten-Treiber: igdumd64 igd10umd64 igdumdx32 igd10umd32 Karten-Treiber (GPU #2): nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um Subsys-ID: 14321043 Subsys-ID (GPU #2): 14321043 Treiber-Datum: 4-10-2011 Treiber-Datum (GPU #2): 8-29-2013 Treiber-Version: 8.15.10.2361 Treiber-Version (GPU #2): 9.18.13.2702 WebGL-Renderer: Google Inc. -- ANGLE (Intel(R) HD Graphics Direct3D11 vs_4_0 ps_4_0) windowLayerManagerRemote: true AzureCanvasBackend: skia AzureContentBackend: cairo AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0

Wichtige modifizierte Einstellungen

accessibility.typeaheadfind.flashBar: 0 browser.cache.disk.capacity: 358400 browser.cache.disk.filesystem_reported: 1 browser.cache.disk.smart_size.first_run: false browser.cache.disk.smart_size.use_old_max: false browser.cache.frecency_experiment: 1 browser.download.folderList: 2 browser.download.importedFromSqlite: true browser.download.manager.alertOnEXEOpen: true browser.places.smartBookmarksVersion: 7 browser.privatebrowsing.autostart: true browser.search.suggest.enabled: false browser.search.useDBForOrder: true browser.sessionstore.restore_on_demand: false browser.startup.homepage_override.buildID: 20151221130713 browser.startup.homepage_override.mstone: 43.0.2 browser.tabs.warnOnClose: false dom.apps.reset-permissions: true dom.mozApps.used: true extensions.lastAppVersion: 43.0.2 font.internaluseonly.changed: true gfx.blacklist.direct2d: 3 gfx.crash-guard.d3d11layers.appVersion: 43.0.2 gfx.crash-guard.d3d11layers.deviceID: 0x0046 gfx.crash-guard.d3d11layers.driverVersion: 8.15.10.2361 gfx.crash-guard.d3d11layers.feature-d2d: false gfx.crash-guard.d3d11layers.feature-d3d11: true gfx.crash-guard.glcontext.gfx.driver-init.direct3d11-angle: true gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle: true gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-force-d3d11: false gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-force-warp: false gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-try-d3d11: true gfx.crash-guard.status.d3d11layers: 2 gfx.crash-guard.status.d3d9video: 2 gfx.crash-guard.status.glcontext: 2 gfx.driver-init.appVersion: 42.0 gfx.driver-init.deviceID: 0x0046 gfx.driver-init.driverVersion: 8.15.10.2361 gfx.driver-init.feature-d2d: false gfx.driver-init.feature-d3d11: true gfx.driver-init.status: 2 media.gmp-manager.buildID: 20151221130713 media.gmp-manager.lastCheck: 1450777201 media.hardware-video-decoding.failed: false network.auth.allow-subresource-auth: 2 network.cookie.prefsMigrated: true network.predictor.cleaned-up: true places.database.lastMaintenance: 1451001380 places.history.expiration.transient_current_max_pages: 17000 plugin.disable_full_page_plugin_for_types: application/pdf plugin.importedState: true print.printer_PDFCreator.print_bgcolor: false print.printer_PDFCreator.print_bgimages: false print.printer_PDFCreator.print_colorspace: print.printer_PDFCreator.print_command: print.printer_PDFCreator.print_downloadfonts: false print.printer_PDFCreator.print_duplex: 1515870810 print.printer_PDFCreator.print_edge_bottom: 0 print.printer_PDFCreator.print_edge_left: 0 print.printer_PDFCreator.print_edge_right: 0 print.printer_PDFCreator.print_edge_top: 0 print.printer_PDFCreator.print_evenpages: true print.printer_PDFCreator.print_footercenter: print.printer_PDFCreator.print_footerleft: &PT print.printer_PDFCreator.print_footerright: &D print.printer_PDFCreator.print_headercenter: print.printer_PDFCreator.print_headerleft: &T print.printer_PDFCreator.print_headerright: &U print.printer_PDFCreator.print_in_color: true print.printer_PDFCreator.print_margin_bottom: 0.5 print.printer_PDFCreator.print_margin_left: 0.5 print.printer_PDFCreator.print_margin_right: 0.5 print.printer_PDFCreator.print_margin_top: 0.5 print.printer_PDFCreator.print_oddpages: true print.printer_PDFCreator.print_orientation: 0 print.printer_PDFCreator.print_page_delay: 50 print.printer_PDFCreator.print_paper_data: 9 print.printer_PDFCreator.print_paper_height: 11,00 print.printer_PDFCreator.print_paper_name: print.printer_PDFCreator.print_paper_size_type: 0 print.printer_PDFCreator.print_paper_size_unit: 1 print.printer_PDFCreator.print_paper_width: 8,50 print.printer_PDFCreator.print_plex_name: print.printer_PDFCreator.print_resolution: 1515870810 print.printer_PDFCreator.print_resolution_name: print.printer_PDFCreator.print_reversed: false print.printer_PDFCreator.print_scaling: 1,00 print.printer_PDFCreator.print_shrink_to_fit: true print.printer_PDFCreator.print_to_file: false print.printer_PDFCreator.print_unwriteable_margin_bottom: 0 print.printer_PDFCreator.print_unwriteable_margin_left: 0 print.printer_PDFCreator.print_unwriteable_margin_right: 0 print.printer_PDFCreator.print_unwriteable_margin_top: 0 privacy.popups.showBrowserMessage: false privacy.sanitize.migrateFx3Prefs: true storage.vacuum.last.index: 1 storage.vacuum.last.places.sqlite: 1450742618

Wichtige nicht veränderbare Einstellungen

JavaScript

Inkrementelle GC: true

Barrierefreiheit

Aktiviert: false Barrierefreiheit verhindern: 0

Bibliotheken-Versionen

NSPR Minimal vorausgesetzte Version: 4.10.10 Verwendete Version: 4.10.10

NSS Minimal vorausgesetzte Version: 3.20.2 Basic ECC Verwendete Version: 3.20.2 Basic ECC

NSSSMIME Minimal vorausgesetzte Version: 3.20.2 Basic ECC Verwendete Version: 3.20.2 Basic ECC

NSSSSL Minimal vorausgesetzte Version: 3.20.2 Basic ECC Verwendete Version: 3.20.2 Basic ECC

NSSUTIL Minimal vorausgesetzte Version: 3.20.2 Verwendete Version: 3.20.2

Experimentelle Funktionen

can you try to replicate this behaviour when you launch firefox in safe mode once? if not, maybe one of the proxy related addons is interfering here...

Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

I opened Firefox in safe mode (you meant Firefox's safe mode, right?) and the same happened, i couldn't open any webpage.

I just restored Firefox with the button underneath the "Safe Mode" button and now it works again. So it has to be some add-on. I don't know which add-on it was.

Thank you very much for your help, guys :) I appreciate that absolutely.

Best regards, Wito