FRITZ!Box 6840 LTE – Service - Knowledge Base

FRITZ!Box 6840 LTE – Service

Problem when updating FRITZ!OS: "Info" LED or several LEDs flash constantly

When updating FRITZ!OS, the restart procedure does not finish and the FRITZ!Box freezes.

In this case

  • all LEDs or only the "Info" LED flash(es) red or yellow
  • you may not be able to open the FRITZ!Box user interface (
  • only a white page with the error message "firmwarecfg: ERROR Error: opening page ../html/index.html" may be displayed in your web browser.

Important:Some of the settings described here are only displayed if the advanced view is enabled in the user interface.

Simply proceed as described below. After each measure, check whether the issue persists.

1 Preparations

The following preparations are necessary for the measures below. They always must be carried out:

Restarting the FRITZ!Box

  1. Unplug your FRITZ!Box by removing the power cable from the electrical outlet.
  2. Plug it in again after 5 seconds.

    Note:The FRITZ!Box settings remain intact. The restart will take about 2 minutes. During this time, you cannot access the FRITZ!Box.

Clearing the cache of your web browser

  • Clear the cache of your web browser:
      • Google Chrome
        1. Click the button (Customize and control Google Chrome) on the top right of Chrome.
        2. Click "More tools" and then "Clear browsing data...".
        3. Select "the beginning of time" in the "Clear browsing data" window.
        4. Select "Cookies and other site and plugin data" and "Cached images and files".
        5. Click "Clear browsing data".
      • Mozilla Firefox
        1. Click the (open menu) button on the top right of Firefox.
        2. Click "History" and then "Clear Recent History".
        3. Select "Everything" and click "Clear Now".
      • Microsoft Edge
        1. Click the button (More actions) in the top right corner of Edge and then click "Settings".
        2. Click "Choose what to clear" under "Clear browsing data".
        3. Enable the option "Cached data and files" and click "Clear".
      • Microsoft Internet Explorer
        1. Click the button (tools) on the top right of the Internet Explorer.
        2. Click "Internet Options" and then "General".
        3. Click the "Delete" button.
        4. Enable the option "Temporary Internet files" and click "Delete".
      • Apple Safari
        1. Click "Safari" in Safari's menu bar and then click "Preferences".
        2. Click "Advanced" in the settings and enable the option "Show 'Develop' menu in menu bar".
        3. Click "Develop" in the menu bar and then click "Empty Caches".
        4. Click "Safari" in the menu bar and then click "Reset Safari".
        5. Click the "Reset" button in the next window.

2 Checking whether the update was successful

  1. Open the FRITZ!Box user interface.
    • If the user interface still does not open several minutes after the "Info" LED has gone out:
      • Use the recovery tool to reset the FRITZ!Box. The recovery tool then installs the update.
  2. Check which FRITZ!OS version is displayed on the "Overview" page.
    • If the new version is displayed, then the update was successful.
    • If an old version is displayed:
      • Repeat the online update procedure.
        • If the online update is unsuccessful, perform a manual update as described in the next section.

3 Repeating the update process

Downloading the FRITZ!OS file again

The FRITZ!OS file may not be suitable for your FRITZ!Box, or the file may not have been downloaded completely. Therefore, download the file again:

  1. Call up in your web browser.
  2. Switch to the folder for your FRITZ!Box model, then to the subfolder "firmware", and then to the folder named "english".

    Note:The complete model name of your FRITZ!Box is displayed in the FRITZ!Box user interface on the "Overview" page and on the underside of the device.

  3. Download the latest FRITZ!OS version for your FRITZ!Box with the file extension ".image" to the computer.

Clearing Internet connection and closing all active programs

ATTENTION!Only disable firewalls when updating FRITZ!OS and re-enable them before establishing an Internet connection. This software protects your computer from attacks from the Internet and prevents other threats (for example computer viruses) from being executed.

  1. Remove the SIM card from the card slot on your FRITZ!Box to clear the Internet connection.
  2. Close all active programs running in the background such as virus scanners, firewalls, etc.

Connecting the FRITZ!Box with the computer

  1. Use the network cable included with delivery to connect the computer directly to a "LAN" port on the FRITZ!Box. 
  2. Clear all other connections between your FRITZ!Box and network devices or USB devices.

Updating the firmware manually

  1. Click "System" in the FRITZ!Box user interface.
  2. Click "Update" or "Firmware Update" in the "System" menu.
  3. Click on the "FRITZ!OS File" or "Firmware File" tab.
  4. Click "Save Settings".

    Note:Save your FRITZ!Box settings again under "System > Backup" right after successfully completing the installation. Then you can always restore it to a working configuration.

  5. Click the "Browse..." or "Choose File" button.
  6. Select the FRITZ!OS file that you downloaded (image file) and click the "Open" button.
  7. Click the "Start Update" button.

4 Resetting the FRITZ!Box

Saving the FRITZ!Box settings

Applying the recovery tool

Restoring the FRITZ!Box settings