Error with spm.Smooth on Windows (TypeError: environment can only contain strings)

[JohannesWiesner]

Summary

I am running into the following error when attempting to use spm.Smooth() on Windows 10 using a bare-metal installation.

Actual behavior

Traceback (most recent call last):

  File "<ipython-input-1-90c4b46891bb>", line 11, in <module>
    smooth.run()

  File "C:\Users\Johannes.Wiesner\.conda\envs\csp\lib\site-packages\nipype\interfaces\base\core.py", line 375, in run
    self._check_version_requirements(self.inputs)

  File "C:\Users\Johannes.Wiesner\.conda\envs\csp\lib\site-packages\nipype\interfaces\base\core.py", line 275, in _check_version_requirements
    if names and self.version:

  File "C:\Users\Johannes.Wiesner\.conda\envs\csp\lib\site-packages\nipype\interfaces\spm\base.py", line 358, in version
    info_dict = Info.getinfo(

  File "C:\Users\Johannes.Wiesner\.conda\envs\csp\lib\site-packages\nipype\interfaces\spm\base.py", line 227, in getinfo
    out = mlab.run()

  File "C:\Users\Johannes.Wiesner\.conda\envs\csp\lib\site-packages\nipype\interfaces\base\core.py", line 419, in run
    runtime = self._run_interface(runtime)

  File "C:\Users\Johannes.Wiesner\.conda\envs\csp\lib\site-packages\nipype\interfaces\matlab.py", line 170, in _run_interface
    runtime = super(MatlabCommand, self)._run_interface(runtime)

  File "C:\Users\Johannes.Wiesner\.conda\envs\csp\lib\site-packages\nipype\interfaces\base\core.py", line 812, in _run_interface
    runtime = run_command(runtime, output=self.terminal_output)

  File "C:\Users\Johannes.Wiesner\.conda\envs\csp\lib\site-packages\nipype\utils\subprocess.py", line 103, in run_command
    proc = Popen(

  File "C:\Users\Johannes.Wiesner\.conda\envs\csp\lib\site-packages\spyder_kernels\customize\spydercustomize.py", line 105, in __init__
    super(SubprocessPopen, self).__init__(*args, **kwargs)

  File "C:\Users\Johannes.Wiesner\.conda\envs\csp\lib\subprocess.py", line 854, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,

  File "C:\Users\Johannes.Wiesner\.conda\envs\csp\lib\subprocess.py", line 1307, in _execute_child
    hp, ht, pid, tid = _winapi.CreateProcess(executable, args,

TypeError: environment can only contain strings

Expected behavior

No error.

How to replicate the behavior

Probably (?) setting up a bare metal installation with Windows 10, MATLAB R2020a, SPM12 & nipype

Script/Workflow details

import nipype.interfaces.spm as spm
smooth = spm.Smooth()
smooth.inputs.in_files = "C:/Users/Johannes.Wiesner/Documents/test_scripts/mwp1sub-A00036142_ses-20050101_acq-mprage_run-01_T1w.nii"
smooth.inputs.fwhm = [4, 4, 4]
smooth.run() 

Platform details:

{'commit_hash': '%h',
 'commit_source': 'archive substitution',
 'networkx_version': '2.4',
 'nibabel_version': '3.1.1',
 'nipype_version': '1.5.1',
 'numpy_version': '1.18.5',
 'pkg_path': 'C:\\Users\\Johannes.Wiesner\\.conda\\envs\\csp\\lib\\site-packages\\nipype',
 'scipy_version': '1.5.0',
 'sys_executable': 'C:\\Users\\Johannes.Wiesner\\.conda\\envs\\csp\\python.exe',
 'sys_platform': 'win32',
 'sys_version': '3.8.3 (default, Jul  2 2020, 17:30:36) [MSC v.1916 64 bit '
                '(AMD64)]',
 'traits_version': '6.1.0'}

Execution environment

• My python environment outside container

This issue is much likely to be related to #2958 and #2509

[effigies]

Thanks. Closing as a duplicate of #2509 and will be aiming to resolve it in the next release. Please follow that discussion. If you have the time to test the proposed fix, that would be great.