New plugin error from demux

I am attempting to demultiplex paired-end ITS data using the following command in qiime2 version 2017.11:

qiime demux emp-paired \
  --i-seqs pe.multplx.qza \
  --m-barcodes-file yeastcycles-metadata.txt \
  --m-barcodes-category BarcodeSequence \
  --o-per-sample-sequences pe-demux.qza

but am receiving the following error:

Plugin error from demux:
  'NoneType' object has no attribute 'strip'
Debug info has been saved to /tmp/qiime2-q2cli-err-cmfef8iu.log

I have run this command before with success using similar data so I am not sure what the issue might be!

Thank you,


Just a quick comment on this. I spoke with @Sydney_Morgan in person (same uni) regarding her issue. Not sure if this relates to the actual error message she is seeing but from a quick glance it looked to me that her forward and reverse reads fastq files were significantly different in size. I know they don’t have to be exact but they were different by a couple of folds. I suspected that the files may have been transferred incompletely when they were transferred on a FAT32 format USB between computers (4G limit?). So I suggested that she try transferring the files again on an NTSF format and try joining those files before trying demultiplexing them.
Again, not sure if this would deal with that specific error but thought I’d update here anyways in case.


Hey @Sydney_Morgan,

Thanks @Mehrbod_Estaki for the suggestion. I think you are correct in what’s happening.

It looks like the code is trying to strip some trailing whitespace, but it hit an end-of-file in the middle of a fastq record (because of the incomplete transfer).

Keep us posted if re-transferring the data doesn’t fix it!

1 Like

Thanks for the help! I re-transferred the files and that seems to have done the trick.


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