6. Troubleshooting client problems

6.1. Windows client fails to start

6.2. Tablet upload fails with error “Read timed out”

Likely problem: slow network, large BLOB (binary large object – e.g. a big photo). For example, in one of our tests a BLOB took more than 17 s to upload, so the tablet needs to wait at least that long after starting to send it. Increase the tablet’s network timeout (e.g. to 60000 ms or more) in Settings → Server settings.

6.3. A photo-based task says “No camera”

CamCOPS asks Qt for available cameras. This message indicates that none were found. This is usually a hardware configuration problem.

  • Under Linux, run cheese; does this find a camera?
  • If you’re using a laptop, does it have a special function key combination to enable/disable the camera?

6.4. What if it crashes?

This shouldn’t happen; please note down any error details and let us know! To forcibly stop and restart the app:

Android 4.3

  • Settings → More → Application Manager → CamCOPS → Force stop
  • Then start the app again as usual.

iOS 7

  • Double-click the Home button
  • Swipe left/right until you find the CamCOPS app’s preview
  • Swipe the app preview up to close it
  • Then start the app again as usual


  • Close it as usual; if it refuses to close, kill it via the Task Manager.