[Bug]: Fail to read NWB file where TimeZone is missing from session_start_time

[ehennestad]

What happened?

Not sure if this is a bug, but it seems strict to enforce TimeZone on read.

Steps to Reproduce

In MATLAB:

nwb = NwbFile( ...
    'session_description', 'Simple demo file', ...
    'identifier', 'test_file', ...
    'session_start_time', datetime("now"), ...
    'timestamps_reference_time', datetime("now"));
nwbExport(nwb, 'temp.nwb')

In python:

from pynwb import NWBHDF5IO

io = NWBHDF5IO('temp.nwb', mode="r")
nwbfile = io.read()

Traceback

Error using objectmapper>construct
Python Error: ConstructError: (root GroupBuilder {'attributes': {'namespace': 'core', 'neurodata_type': 'NWBFile', 'nwb_version': '2.8.0',
'object_id': 'ad86c34b-4de3-4352-a698-d112fe26f032'}, 'groups': {'acquisition': root/acquisition GroupBuilder {'attributes': {}, 'groups': {},
'datasets': {}, 'links': {}}, 'analysis': root/analysis GroupBuilder {'attributes': {}, 'groups': {}, 'datasets': {}, 'links': {}}, 'general':
root/general GroupBuilder {'attributes': {}, 'groups': {'devices': root/general/devices GroupBuilder {'attributes': {}, 'groups': {},
'datasets': {}, 'links': {}}, 'extracellular_ephys': root/general/extracellular_ephys GroupBuilder {'attributes': {}, 'groups': {},
'datasets': {}, 'links': {}}, 'intracellular_ephys': root/general/intracellular_ephys GroupBuilder {'attributes': {}, 'groups': {},
'datasets': {}, 'links': {}}, 'optogenetics': root/general/optogenetics GroupBuilder {'attributes': {}, 'groups': {}, 'datasets': {}, 'links':
{}}, 'optophysiology': root/general/optophysiology GroupBuilder {'attributes': {}, 'groups': {}, 'datasets': {}, 'links': {}}}, 'datasets':
{}, 'links': {}}, 'intervals': root/intervals GroupBuilder {'attributes': {}, 'groups': {}, 'datasets': {}, 'links': {}}, 'processing':
root/processing GroupBuilder {'attributes': {}, 'groups': {}, 'datasets': {}, 'links': {}}, 'scratch': root/scratch GroupBuilder
{'attributes': {}, 'groups': {}, 'datasets': {}, 'links': {}}, 'stimulus': root/stimulus GroupBuilder {'attributes': {}, 'groups':
{'presentation': root/stimulus/presentation GroupBuilder {'attributes': {}, 'groups': {}, 'datasets': {}, 'links': {}}, 'templates':
root/stimulus/templates GroupBuilder {'attributes': {}, 'groups': {}, 'datasets': {}, 'links': {}}}, 'datasets': {}, 'links': {}}},
'datasets': {'file_create_date': root/file_create_date DatasetBuilder {'attributes': {}, 'data': <StrDataset for HDF5 dataset
"file_create_date": shape (1,), type "|O">}, 'identifier': root/identifier DatasetBuilder {'attributes': {}, 'data': 'test_file'},
'session_description': root/session_description DatasetBuilder {'attributes': {}, 'data': 'Simple demo file'}, 'session_start_time':
root/session_start_time DatasetBuilder {'attributes': {}, 'data': '2025-03-05T15:08:07.380042'}, 'timestamps_reference_time':
root/timestamps_reference_time DatasetBuilder {'attributes': {}, 'data': '2025-03-05T15:08:07.380880'}}, 'links': {}}, "Could not construct
NWBFile object due to: 'timestamps_reference_time' must be a timezone-aware datetime object.")

Operating System

macOS

Python Executable

Python

Python Version

3.9

Package Versions

No response

Code of Conduct

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[stephprince]

I think in this particular case it would be ok to give a warning about the timestamps_reference_time on read, and error only when creating a new NWBFile without a timezone-aware timestamps_reference_time. However, I am not sure if there are additional downstream implications.

@rly do you have any thoughts? I know at one point timestamps_reference_time was going to be allowed to be timezone-naive in general, but that change had to be reverted in #1908 and was part of other timezone related changes