Steps to reproduce:

$ beat cache clear
$ beat exp pull amohammadi/tutorial/eigenface/1/atnt-eigenfaces-67-comp
$ beat exp run amohammadi/tutorial/eigenface/1/atnt-eigenfaces-67-comp
Index for database atnt/5 not found, building it
lib/python3.7/site-packages/setuptools/distutils_patch.py:26: UserWarning: Distutils was imported before Setuptools. This usage is discouraged and may exhibit undesirable behaviors or errors. Please use Setuptools' objects directly or at least import Setuptools first.
  "Distutils was imported before Setuptools. This usage is discouraged "
Index for database atnt/5 not found, building it
Index for database atnt/5 not found, building it
Running `amohammadi/pca/1' for block `linear_machine_training'
Start the execution of 'amohammadi/pca/1'
Block did not execute properly - outputs were reset
  Standard output:
    
  Standard error:
    
  Captured user error:
    File "lib/python3.7/site-packages/bob/io/base/__init__.py", line 143, in load
        return File(inputs, 'r').read()
    RuntimeError: File - constructor: C++ exception caught: 'file '/path_to_db_folder/att_faces/s1/1.pgm' is not readable'
  Captured system error:
    
Error: Error occured: returned value is 1
Removing cache files: No data written

• change the json file prefix/databases/atnt/5.json of the database and fix the the root_folder
• run the experiment again:

$ beat exp run amohammadi/tutorial/eigenface/1/atnt-eigenfaces-67-comp
    RuntimeError: File - constructor: C++ exception caught: 'file '/path_to_db_folder/att_faces/s1/1.pgm' is not readable'