Android Apps show "Hold Tight...", black screen in place of videos or "Failed to play video to image" error message

Our apps which can be used offline and which include the Hazard Perception function need to download additional content (the videos and Road Sign images) after the initial download - this is in a "OBB" file which is ultimately stored in the /Android/obb folder named for the app.

When this additional file is downloaded depends on your version of Android:

  • Later versions of Android download the additional file immediately after the application and show this action in the pull down notification bar or in the Google Play app
  • Earlier versions of Android download the additional file when the app is first started and show the following black screen with white text reading "Downloading Additional Files" with a % that increases

When a relevant app updates you may see the following screen ("Hold tight... We're downloading all the additional files you need to start revising for your test!") when you next start the app:


If the above appears and the % counter doesn't increase:

  1. Check that you're connected via WiFi (Google Play will delay the download if you're connected via 3G/4G to minimise the risk of you incurring charges for downloading large amounts of data).
  2. If the additional file download remains at 0%:
    1. Power your device off and back on
    2. Connect to the Internet via WiFi and to mains power
    3. Start the app again.
  3. If the additional file download remains at 0% or "Unknown State" is reported:
    1. Close the app
    2. Select:
      • "Android Settings"
      • "Apps"
      • Select the app you're using, e.g. "Theory 4 in 1" or "Hazard Perception..."
      • "Force Stop"
      • "Storage"
      • "Clear Data/Storage"
      • "Clear Cache"
    3. Connect to the Internet via WiFi and to mains power
    4. Start the app again.
  4. If the problem still persists, uninstall and reinstall the app - no need to pay again.
    1. Uninstall the existing app
      Note: You'll lose your progress to date.
    2. Check your device's date and time is correct
    3. Check sufficient free storage is available (~1.2GB)
      • When using an Android device, the app can only be installed to "internal" memory - if you've added expansion memory to your Android device via an SD card this can only be used for the app if the device is running Android 6 or later and you've reformatted the SD card as "internal" (instead of "portable") memory. Uninstall other apps, or more files to portable expansion memory to create sufficient free storage space if necessary.
    4. Clear the Google Play Store app's and Google Play Services caches - this resolves many Google Play issues (the process and menu names may vary slightly depending on your Android version):
      • Select "Settings", "Applications/Apps", "Manage applications/All Apps" then:
        • For each of "Google Play Store", "Google Play Services" and "Google Services Framework", touch the name and then:
          • Touch "Storage" - might not be necessary
          • Touch "Clear Cache" and confirm
          • Touch "Back"
      • Close "Settings" (or press "Home" to hide settings)
    5. Power your device off and back on (not just to sleep)
    6. Review your battery status, if it is low connect your device to a power supply
    7. Connect via WiFi
      Google Play will by default wait for a WiFi connection before downloading such a large app, primarily to reduce the likelihood of your incurring data download charges for 3G/4G download but also because WiFi connections tend to be more stable and are often faster.
    8. Retry the download and install, depending on the app you've purchased:
    9. Start the app and if you see a "Hold Tight, additional file downloading" message, wait and ensure the % increases to 100% before you then continue - this additional content is the video portion of the hazard perception component and the images for the road signs component.

If that additional content isn't downloaded then the following issues may occur:

  • you only get a black screen or "Failed to play video to image, could not get video width or height" error message when attempting to play a hazard perception video.
  • images are missing from the road sign app

Try uninstalling and reinstalling the app and check whether that additional content is completely downloaded when you then first restart the app.

This additional content is quite large - we recommend downloading via a WiFi link to a stable landline Internet connection so that you are less likely to incur data download charges or to lose connection during the download process.

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