# EEG cnt file error

**URL:** <https://mne.discourse.group/t/eeg-cnt-file-error/2762>\
**Category:** Support & Discussions\
**Created:** [February 28, 2021, 3:51pm UTC](https://mne.discourse.group/t/eeg-cnt-file-error/2762 "2021-02-28T15:51:47Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![sKinreich](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/skinreich/32/232_2.png) [@sKinreich](https://mne.discourse.group/u/sKinreich)\
**Post date:** [February 28, 2021, 3:51pm UTC](https://mne.discourse.group/t/eeg-cnt-file-error/2762/1 "2021-02-28T15:51:47Z")

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MNE version 0.22  
I’m getting the following error reading the file with  
raw = mne.io.read\_raw\_cnt(filename, preload=True)

RuntimeWarning: Could not define the number of bytes automatically. Defaulting to 2.  
Do you know what does that mean ?

Thanks !!

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**Author:** ![agramfort](https://avatars.discourse-cdn.com/v4/letter/a/7c8e57/32.png) [@agramfort](https://mne.discourse.group/u/agramfort)\
**Post date:** [February 28, 2021, 4:15pm UTC](https://mne.discourse.group/t/eeg-cnt-file-error/2762/2 "2021-02-28T16:15:07Z")

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it’s not an error but a warning.

does your data long wrong?

Alex

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**Author:** ![sKinreich](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/skinreich/32/232_2.png) [@sKinreich](https://mne.discourse.group/u/sKinreich)\
**Post date:** [March 1, 2021, 2:47pm UTC](https://mne.discourse.group/t/eeg-cnt-file-error/2762/3 "2021-03-01T14:47:18Z")

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Everything seems right and the file did upload. It just presents this runtime error which I want to be sure

To not obscure the data.

I might run some tests to see that the uploaded file is the same as the cnt file (upload the file to eeglab and compare).

Do you have any other suggestions ?

Thanks for any idea.

Sivan

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**Author:** ![agramfort](https://avatars.discourse-cdn.com/v4/letter/a/7c8e57/32.png) [@agramfort](https://mne.discourse.group/u/agramfort)\
**Post date:** [March 1, 2021, 8:17pm UTC](https://mne.discourse.group/t/eeg-cnt-file-error/2762/4 "2021-03-01T20:17:07Z")

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just ignore the warning?

A

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**Author:** ![richard](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/richard/32/15_2.png) [@richard](https://mne.discourse.group/u/richard)\
**Post date:** [March 1, 2021, 8:38pm UTC](https://mne.discourse.group/t/eeg-cnt-file-error/2762/5 "2021-03-01T20:38:45Z")

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Hello, typically if something goes wrong during data import, it is **very** obvious. If you plot the data using `raw.plot()` and it seems to look normal, **it most likely is** , and you can stop worrying. 🙂

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<div class="post-metadata">

**Author:** ![sKinreich](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/skinreich/32/232_2.png) [@sKinreich](https://mne.discourse.group/u/sKinreich)\
**Post date:** [March 1, 2021, 8:51pm UTC](https://mne.discourse.group/t/eeg-cnt-file-error/2762/6 "2021-03-01T20:51:18Z")

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Thank you !!! The data seems correct after loading.