[rospack] Error: the rosdep view is empty: call 'sudo rosdep init' and 'rosdep update'

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Using following order I solved for Ubuntu 20.04 and ROS Noetic my problem after getting:

[rospack] Error: the rosdep view is empty: call 'sudo rosdep init' and 'rosdep update'

1:

$ rosdep update

Command 'rosdep' not found, but can be installed with:

sudo apt install python3-rosdep2

2:

$ sudo apt install python3-rosdep2

0 upgraded, 1 newly installed, 150 to remove and 301 not upgraded. Need to get 52.8 kB of archives. After this operation, 89.6 MB disk space will be freed. Do you want to continue? [Y/n] y

3:

$ rosdep update

4:

$ sudo apt install ros-noetic-desktop-full

0 upgraded, 150 newly installed, 1 to remove and 301 not upgraded. Need to get 16.8 MB of archives. After this operation, 89.6 MB of additional disk space will be used. Do you want to continue? [Y/n] y

Hope it helps.

try 'sudo apt-get install python3-rosdep'. This should fix the issue

Follow the official wiki (you're on ubuntu 18.04, so follow the tutorial for ROS Melodic, which targets Ubuntu 18.04 among others). There you see python-rosdep, without the trailing "2".

Btw, I totally understand where the confusion about python-rosdep2 came from. The following is what I found:

• python-rosdep2 (0.11.8-1) for 18.04 is "default" on the official packages.ubuntu.com, where Ubuntu gets a lot of packages from. https://packages.ubuntu.com/bionic/py....
• Official way in ROS to obtain rosdep package is from packages.ros.org (which is what "source list" points to). There I see python-rosdeppackage at http://packages.ros.org/ros/ubuntu/di... and its version is 0.19.0 (, which is much larger than python-rosdep2)

Package: python-rosdep
Priority: optional
Section: python
Installed-Size: 21
Maintainer: Tully Foote, Ken Conley <tfoote@osrfoundation.org>
Architecture: all
Version: 0.19.0-1
Depends: python (<< 2.8), python (>= 2.7), python-catkin-pkg, python-rosdistro, python-rospkg, python-yaml, python:any, python-rosdep-modules (>= 0.19.0)
Conflicts: python-rosdep2, python3-rosdep, python3-rosdep2
Filename: pool/main/p/python-rosdep/python-rosdep_0.19.0-1_all.deb
SHA512: c9b816bd1eb96b068d67e4cf877ab7c22ecacf00ece5e4f525052ceb2eb0ffc86e334259d29c84afa21318e33d291c2cceb6bd71b14b2b424c75c47288629c83
Size: 3216
SHA256: 1f8cf18fc1a54a95dfb0c44a31f99053a0bd82ab11b4515df48fd2ba02fde4d4
SHA1: aa835b94c89afa1724855ba25e727a2580bcbfb3
MD5sum: 221684e20ca39200d6ed1f4c8eafb869
Description: rosdep package manager abstraction tool for ROS
 Command-line tool for installing system dependencies on a variety of platforms.

My question to rosdep maintainers, assuming python-rosdep2 was uploaded to packages.ubuntu.com by them but I'm not entirely sure, is why these are done? I guess this may the same discussion discourse.ros.org#10902/, so maybe we should continue on discourse or Github.