I've been trying to install the packages necessary to play with shape recognition with a camera. Virtually all sites recommend using opencv, and tell, like here, here and here, to install it with

apt‐get install python‐opencv

Sometimes with sudo. They drop the command without a second thought, like it should have no reason to fail. The problem is that my apt-get does not find the packages.

$ > sudo apt-get install python‐opencv
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package python‐opencv

I guess I'm missing one or more lines in /etc/apt/sources.list but could not find which ones by STFW. Here's the contents of the file right now, which came default with the install of raspbian:

> cat /etc/apt/sources.list
deb http://mirrordirector.raspbian.org/raspbian/ stretch main contrib non-free rpi
# Uncomment line below then 'apt-get update' to enable 'apt-get source'
# deb-src http://archive.raspbian.org/raspbian/ stretch main contrib non-free rpi

I've tried to uncomment the deb-src line and add the following line I found somewhere, to no avail:

deb http://de.archive.ubuntu.com/ubuntu precise main restricted universe

Running sudo apt-get update works for some time, ignores (lines starting with Ign?) many packages, gets a handful of packages, then gives the following error, which I'm not sure is critical:

W: The repository 'http://de.archive.ubuntu.com/ubuntu precise Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/precise/main/binary-all/Packages.gz  Redirection loop encountered
E: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/precise/main/binary-armhf/Packages  404  Not Found [IP: 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.

I have an 8GB not full SDCard that I formatted by following the instructions under Download NOOBS files then drag and drop here.

What am I missing?

  • try to follow this link: milq.github.io/install-opencv-ubuntu-debian bye.
    – init0
    Oct 26, 2017 at 19:20
  • 1
    Your sources list looks OK. Have you recently tried sudo apt-get update? If not, try that, then run the install again. Perhaps your package lists are out of date.
    – Aurora0001
    Oct 26, 2017 at 19:37

1 Answer 1


Instead of formatting the SDCard then copying the NOOBS files to it, I flashed it with an image, as described under Download and image Raspbian directly here. Then everything went smoothly.

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