Consistently getting mysterious error "error uploading artifacts"

I consistently get an error “error uploading artifacts”, and there is no other information to debug the problem.

The files are very small.

Each container writes to a different directory. (so the filenames do not conflict)

What can I do?

Here is a link to a build that shows this problem:

Is there any chance its a permissions issue?

What permission should I use for creating the artifacts?
I am doing everything with the default user.

I have also verified that the artifacts are created correctly by copying them to one of my servers.

So I am inclined to say that this is Circle bug.

Hello @AndreaCensi,

The artifacts storage must have read/write access to the files which you intend to store.

Please be sure that your user has read/write access to the test artifacts.

Do you mean I should chown the files to a different user?

I am not changing user from the default (ubuntu).

See for example this build

The error is

Collecting 89 build artifacts
Error uploading artifacts

I tried to log in and check the file permissions:

(venv-system) ubuntu@box> 834:~/mcdp$ vdir !$
total 116
drwxrwxr-x 1 ubuntu ubuntu 200 Feb 7 13:59 compmake-stats
drwxrwxr-x 1 ubuntu ubuntu 2792 Feb 7 13:59 comptests-failures
-rw-rw-r-- 1 ubuntu ubuntu 109000 Feb 7 13:59 junit-0.xml
-rw-rw-r-- 1 ubuntu ubuntu 1333 Feb 7 13:59 pip_freeze_all-0.txt
-rw-rw-r-- 1 ubuntu ubuntu 1333 Feb 7 13:59 pip_freeze_local-0.txt

Should the permissions be different?

How about to try packaging all (89) artifacts into one tarball before uploading?