# Dada2 very slow step

**URL:** https://forum.qiime2.org/t/dada2-very-slow-step/7136
**Category:** User Support
**Tags:** dada2
**Created:** [November 22, 2018, 6:13pm UTC](https://forum.qiime2.org/t/dada2-very-slow-step/7136 "2018-11-22T18:13:16Z")
**Posts on this page:** 1
**Showing post:** 19

<div class="post-metadata">

### Author: ![Nicholas\_Bokulich](https://forum.qiime2.org/user_avatar/forum.qiime2.org/nicholas_bokulich/32/19937_2.png) [@Nicholas\_Bokulich](https://forum.qiime2.org/u/Nicholas_Bokulich)
#### Post date: [December 18, 2018, 8:44pm UTC](https://forum.qiime2.org/t/dada2-very-slow-step/7136/19 "2018-12-18T20:44:19Z")

</div>

Hi @mudbugecology,  
It looks like your demux.qza file did not upload correctly — it is probably too large for the site to handle!

In any case, no news is good news as far as dada2 error messages go. Just leave it running — for large datasets using a single CPU it is not unusual to wait a few days...

---

_[View the full topic](https://forum.qiime2.org/t/dada2-very-slow-step/7136)._