Error raised during denosing step with DADA2

[Nicholas_Bokulich]

Hi @antonioggsousa,
Could you share the quality scores profile for your forward and reverse reads? Are the Q scores by any chance fake? We have seen this same error message occur when fake Q scores are used. See here:

Doing taxonomy analysis and getting abundancies with manifests

If I'm reading the provided sample correctly, this appears to be single-end 454 data with fake quality scores (everything is Q=40). Is that correct? The DADA2 plugin will fail on such data, as it is expecting a range of scores as in real data. While you can run DADA2 on 454 data, it needs the real quality scores. (Note to self: add flag to plugin to allow running w/o quality scores). I am not a Deblur expert, but if this is 454 data you might want to double-check with @wasade on the right way …

Thanks!