ROS Resources: Documentation | Support | Discussion Forum | Index | Service Status | ros @ Robotics Stack Exchange
Ask Your Question


asked 2020-04-02 07:18:56 -0600

lukasjani gravatar image

I'm following an instruction manual, which uses

rosdep install --from-paths src --ignore-src --os=debian:stretch --rosdistro melodic

One of the commands it tries to execute is

apt-get install python-pycrptodome

This returns the error

E: Unable to locate package python-pycryptodome

Which, as far as I know, is because pycryptodome can only be installed using pip. Is there a way to delete or skip this single command in the install chain, as I have already installed pycryptodome (3.9.7) manually?

I'm using a Debian 9.12 stretch VM. Also the warning

ROS_PYTHON_VERSION is unset. Defaulting to 2

should be no problem, as python 2.7.13 is installed.

edit retag flag offensive close merge delete


I'm following an instruction manual, [..]

please always be specific: which instructions are you following?

gvdhoorn gravatar image gvdhoorn  ( 2020-04-02 07:32:36 -0600 )edit

2 Answers

Sort by ยป oldest newest most voted

answered 2020-04-02 07:27:28 -0600

gvdhoorn gravatar image

updated 2020-04-02 07:31:39 -0600

According to, python-pycryptodome is available starting in stretch-backports, and fully in buster. In Ubuntu it's available starting with bionic (here).

Debian 9.12 would be Stretch. So it should at least be available in the backports repository.

If you don't want to use that, you could append --skip-keys="python-pycryptodome" to the rosdep invocation.

Edit: I just checked, and it seems ros/rosdistro#22011 added pycryptodome to the rosdep DB. @Dirk Thomas comments there:

On Debian Stretch the package is only available when using stretch-backports: [..]


We imported the package for Debian Stretch from the backports repo into the ROS repos: ros-infrastructure/reprepro-updater#69.

This seems to imply that if:

  • you have configured as an apt repository on your system, and
  • you run one of the architectures for which the package has been imported

you should be able to resolve the python-pycryptodome dependency using apt.

Do you have the ROS repositories configured? What is the output of apt-cache policy python-pycryptodome?

edit flag offensive delete link more


So what did you end up doing?

gvdhoorn gravatar image gvdhoorn  ( 2020-04-02 07:44:28 -0600 )edit

answered 2021-03-22 08:10:20 -0600

CimeROS gravatar image

I had a similar error:

ERROR: the following rosdeps failed to install
  apt: command [sudo -H apt-get install -y python-pycryptodome] failed

solved this on Debian Strech on RPI3 with pip:

pip install pycryptodome

hope it helps

edit flag offensive delete link more

Question Tools


Asked: 2020-04-02 07:18:56 -0600

Seen: 1,250 times

Last updated: Mar 22 '21