# DADA2 execution halted (Error in table: attempt to make a table with \>= 2^31 elements)

**URL:** https://forum.qiime2.org/t/dada2-execution-halted-error-in-table-attempt-to-make-a-table-with-2-31-elements/11845
**Category:** Technical Support
**Tags:** dada2
**Created:** [October 6, 2019, 2:32pm UTC](https://forum.qiime2.org/t/dada2-execution-halted-error-in-table-attempt-to-make-a-table-with-2-31-elements/11845 "2019-10-06T14:32:38Z")
**Posts on this page:** 6
**Page:** 1

<div class="post-metadata">

### Author: ![potatoo](https://forum.qiime2.org/letter_avatar_proxy/v4/letter/p/a87d85/32.png) [@potatoo](https://forum.qiime2.org/u/potatoo)
#### Post date: [October 6, 2019, 2:32pm UTC](https://forum.qiime2.org/t/dada2-execution-halted-error-in-table-attempt-to-make-a-table-with-2-31-elements/11845/1 "2019-10-06T14:32:38Z")

</div>

I am using DADA2 (Qiime2 2019.7 which is installed within a conda environment in lab server) to denoise a adapter-trimmed 16S rRNA sequence dataset. However, execution halted after four days computation. I got an error message:

> Plugin error from dada2: An error was encountered while running DADA2 in R ( **return code 1** ), please inspect stdout and stderr to learn more.  
> Debug info has been saved to /home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/qiime2-q2cli-err-hpcrjy3c.log

and I checked the debug info in temporary directory, it said (see entire output below):

> **Error in table(pairdf$forward, pairdf$reverse) :  
> attempt to make a table with \>= 2^31 elements**  
> Calls: mergePairs -\> lapply -\> FUN -\> table  
> Execution halted  
> Running external command line application(s). This may print messages to stdout and/or stderr.  
> The command(s) being run are below. These commands cannot be manually re-run as they will depend on temporary files that no longer exist.

After searching for similar problems in qiime2 forum and other websites, I only found the following post: .

> <https://github.com/benjjneb/dada2/issues/641>
>
> \--Hi,
> 
> dada2 failed after one week with:
> Creating output directory: /home/QII…ME/RAW\_DATA/FWD/filtered
> Creating output directory:/home/QIIME/RAW\_DATA/REV/filtered
> 498459920 total bases in 6230749 reads from 1 samples will be used for learning the error rates.
> 467306175 total bases in 6230749 reads from 1 samples will be used for learning the error rates.
> Processing: lib-1
> Sample 1 - 6230749 reads in 5379391 unique sequences.
> Sample 1 - 6230749 reads in 5537794 unique sequences.
> Error in table(pairdf$forward, pairdf$reverse) :
> attempt to make a table with \>= 2^31 elements
> Calls: mergePairs -\> lapply -\> FUN -\> table
> Execution halted
> 
> One week to process only 1 library and it failed. I have 80 libraries to process.
> 
> this is the script i used:
> 
> \#!/usr/bin/env /usr/bin/R-3.5.1/Rscript
> library(dada2)
> pathF \<- "/home/QIIME/RAW\_DATA/FWD"
> pathR \<- "/home/QIIME/RAW\_DATA/REV"
> filtpathF \<- file.path(pathF, "filtered")
> filtpathR \<- file.path(pathR, "filtered")
> fastqFs \<- sort(list.files(pathF, pattern="\_R1.fastq.gz"))
> fastqRs \<- sort(list.files(pathR, pattern="\_R2.fastq.gz"))
> if(length(fastqFs) != length(fastqRs)) stop("Forward and reverse files do not match.")
> filterAndTrim(fwd=file.path(pathF, fastqFs), filt=file.path(filtpathF, fastqFs), rev=file.path(pathR, fastqRs), filt.rev=file.path(filtpathR, fastqRs), minLen=75, truncLen=c(80,75), maxN=c(0,0), maxEE=c(5,5), truncQ=11, rm.phix=c(TRUE, TRUE), compress=TRUE, verbose=TRUE, multithread=TRUE)
> filtFs \<- list.files(filtpathF, pattern="\_R1.fastq.gz", full.names = TRUE)
> filtRs \<- list.files(filtpathR, pattern="\_R2.fastq.gz", full.names = TRUE)
> sample.names \<- sapply(strsplit(basename(filtFs), "\_"), \`\[\`, 1)
> sample.namesR \<- sapply(strsplit(basename(filtRs), "\_"), \`\[\`, 1)
> if(!identical(sample.names, sample.namesR)) stop("Forward and reverse files do not match.")
> names(filtFs) \<- sample.names
> names(filtRs) \<- sample.names
> set.seed(100)
> errF \<- learnErrors(filtFs, nbases=1e4, multithread=TRUE)
> errR \<- learnErrors(filtRs, nbases=1e4, multithread=TRUE)
> mergers \<- vector("list", length(sample.names))
> names(mergers) \<- sample.names
> for(sam in sample.names) {
> cat("Processing:", sam, "\\n")
> derepF \<- derepFastq(filtFs\[\[sam\]\])
> ddF \<- dada(derepF, err=errF, multithread=TRUE)
> derepR \<- derepFastq(filtRs\[\[sam\]\])
> ddR \<- dada(derepR, err=errR, multithread=TRUE)
> merger \<- mergePairs(ddF, derepF, ddR, derepR)
> mergers\[\[sam\]\] \<- merger
> }
> rm(derepF); rm(derepR)
> seqtab \<- makeSequenceTable(mergers)
> saveRDS(seqtab, "/home/QIIME/seqtab.rds")
> 
> I work on computer with 64G of RAM and 16 cores.

However, this post does not provide any feasible solution.

I tried to find some clues in code of dada2. It seems that the error generated from the paired-end merging step, but I don't have any idea to overcome this problem. Would you please guide me to solve this problem?

Thank you for your attention and time.

potatoo

> <https://github.com/benjjneb/dada2/blob/master/R/paired.R>

### computational environment

- Ubuntu 18.04.3 LTS (lab server, RAM: 62GB, CPUs: 4, Cores per CPU: 4, Threads per core: 1)
- Qiime2 2019.7
- conda 4.7.12

### dataset overview

[qiime\_trim\_16s\_HETrim\_191002.qzv](https://forum.qiime2.org/uploads/short-url/8l5hZlhRgusFzsh4z26CPT9odNb.qzv) (338.0 KB)

### command

> export TMPDIR=/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp

> indir=/home/qfwfq/DIMP/data/proc/20190927/qiime\_trim\_16s\_dnmgb\_190927/qiime\_trim\_16s\_HETrim\_190927.qza  
> outdir=/home/qfwfq/DIMP/data/proc/20191002/denoise\_trim\_16s\_dnmgb\_191002

> nohup qiime dada2 denoise-paired   
> --i-demultiplexed-seqs ${indir}   
> --p-trim-left-f 0   
> --p-trim-left-r 0   
> --p-trunc-len-f 0   
> --p-trunc-len-r 0   
> --p-n-threads 4   
> --o-table ${outdir}/table\_denoise\_16s\_dnmgb\_191002.qza   
> --o-representative-sequences ${outdir}/rep\_seqs\_denoise\_16s\_dnmgb\_191002.qza   
> --o-denoising-stats ${outdir}/stats\_denoise\_16s\_dnmgb\_191002.qza \> ${outdir}/denoise\_err\_20191002.txt &

### output message

> Plugin error from dada2: An error was encountered while running DADA2 in R (return code 1), please inspect stdout and stderr to learn more.  
> Debug info has been saved to /home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/qiime2-q2cli-err-hpcrjy3c.log

### qiime2 debug info in temporary directory (qiime2-q2cli-err-hpcrjy3c.log)

> R version 3.5.1 (2018-07-02)  
> Loading required package: Rcpp  
> DADA2: 1.10.0 / Rcpp: 1.0.2 / RcppParallel: 4.4.3
> 
> 1. Filtering .....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
> 2. Learning Error Rates  
> 182577384 total bases in 1055371 reads from 15 samples will be used for learning the error rates.  
> 180475410 total bases in 1055371 reads from 15 samples will be used for learning the error rates.
> 3. Denoise remaining samples .................................................................................Duplicate sequences in merged output.  
> .....................................................Duplicate sequences in merged output.  
> ...................................Duplicate sequences in merged output.  
> ..................................................Duplicate sequences in merged output.  
> .........Duplicate sequences in merged output.  
> .Duplicate sequences in merged output.  
> .....Duplicate sequences in merged output.  
> ...Duplicate sequences in merged output.  
> .............Duplicate sequences in merged output.  
> ...........Duplicate sequences in merged output.  
> ........................................................Duplicate sequences in merged output.  
> .........................Duplicate sequences in merged output.  
> .Duplicate sequences in merged output.  
> ..................Duplicate sequences in merged output.  
> .Duplicate sequences in merged output.  
> .Duplicate sequences in merged output.  
> .........Duplicate sequences in merged output.  
> ................................................Duplicate sequences in merged output.  
> ...............................................................................Duplicate sequences in merged output.  
> ..................................................................................................................................................................................Duplicate sequences in merged output.  
> .................................................................................................................................................................................Duplicate sequences in merged output.  
> ................Duplicate sequences in merged output.  
> ...................................................Duplicate sequences in merged output.  
> .......................................Duplicate sequences in merged output.  
> ...............Duplicate sequences in merged output.  
> ..........................Duplicate sequences in merged output.  
> ............................................................Duplicate sequences in merged output.  
> ..........Duplicate sequences in merged output.  
> ...................Duplicate sequences in merged output.  
> ...............................Duplicate sequences in merged output.  
> ...................Duplicate sequences in merged output.  
> .........Duplicate sequences in merged output.  
> ....Duplicate sequences in merged output.  
> .Duplicate sequences in merged output.  
> ........Duplicate sequences in merged output.  
> ......Duplicate sequences in merged output.  
> .Duplicate sequences in merged output.  
> .....Duplicate sequences in merged output.  
> .Duplicate sequences in merged output.  
> .Duplicate sequences in merged output.  
> ..Duplicate sequences in merged output.  
> .....Duplicate sequences in merged output.  
> ..Duplicate sequences in merged output.  
> .........Duplicate sequences in merged output.  
> ...................................................................Duplicate sequences in merged output.  
> ..Duplicate sequences in merged output.  
> ....Duplicate sequences in merged output.  
> .....Duplicate sequences in merged output.  
> .Duplicate sequences in merged output.  
> .....Duplicate sequences in merged output.  
> .................Duplicate sequences in merged output.  
> .Duplicate sequences in merged output.  
> ..Duplicate sequences in merged output.  
> ....Duplicate sequences in merged output.  
> .....Duplicate sequences in merged output.  
> ..Duplicate sequences in merged output.  
> ....Duplicate sequences in merged output.  
> .........Duplicate sequences in merged output.  
> ..Duplicate sequences in merged output.  
> .............................................Duplicate sequences in merged output.  
> ....Duplicate sequences in merged output.  
> ....Duplicate sequences in merged output.  
> ....Duplicate sequences in merged output.  
> .....................................................................................................................................**Error in table(pairdf$forward, pairdf$reverse)** :  
> **attempt to make a table with \>= 2^31 elements**  
> **Calls: mergePairs -\> lapply -\> FUN -\> table**  
> **Execution halted**  
> Running external command line application(s). This may print messages to stdout and/or stderr.  
> The command(s) being run are below. These commands cannot be manually re-run as they will depend on temporary files that no longer exist.

> Command: run\_dada\_paired.R /home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/tmp3jlyy1il/forward /home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/tmp3jlyy1il/reverse /home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/tmp3jlyy1il/output.tsv.biom /home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/tmp3jlyy1il/track.tsv /home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/tmp3jlyy1il/filt\_f /home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/tmp3jlyy1il/filt\_r 0 0 0 0 2.0 2.0 2 consensus 1.0 4 1000000

> Traceback (most recent call last):  
> File "/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/lib/python3.6/site-packages/q2\_dada2/\_denoise.py", line 234, in denoise\_paired  
> run\_commands([cmd])  
> File "/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/lib/python3.6/site-packages/q2\_dada2/\_denoise.py", line 36, in run\_commands  
> subprocess.run(cmd, check=True)  
> File "/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/lib/python3.6/subprocess.py", line 418, in run  
> output=stdout, stderr=stderr)  
> **subprocess.CalledProcessError** : Command '['run\_dada\_paired.R', '/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/tmp3jlyy1il/forward', '/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/tmp3jlyy1il/reverse', '/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/tmp3jlyy1il/output.tsv.biom', '/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/tmp3jlyy1il/track.tsv', '/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/tmp3jlyy1il/filt\_f', '/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/tmp/tmp3jlyy1il/filt\_r', '0', '0', '0', '0', '2.0', '2.0', '2', 'consensus', '1.0', '4', '1000000']' **returned non-zero exit status 1.**

> During handling of the above exception, another exception occurred:

> Traceback (most recent call last):  
> File "/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/lib/python3.6/site-packages/q2cli/commands.py", line 327, in **call**  
> results = action(\*\*arguments)  
> File "\</home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/lib/python3.6/site-packages/decorator.py:decorator-gen-459\>", line 2, in denoise\_paired  
> File "/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/lib/python3.6/site-packages/qiime2/sdk/action.py", line 240, in bound\_callable  
> output\_types, provenance)  
> File "/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/lib/python3.6/site-packages/qiime2/sdk/action.py", line 383, in _callable\_executor_  
> output\_views = self.\_callable(\*\*view\_args)  
> File "/home/qfwfq/pgm/miniconda3/envs/qiime2-2019.7/lib/python3.6/site-packages/q2\_dada2/\_denoise.py", line 249, in denoise\_paired  
> " and stderr to learn more." % e.returncode)  
> Exception: An error was encountered while running DADA2 in R (return code 1), please inspect stdout and stderr to learn more.

---

<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: [October 8, 2019, 9:11pm UTC](https://forum.qiime2.org/t/dada2-execution-halted-error-in-table-attempt-to-make-a-table-with-2-31-elements/11845/2 "2019-10-08T21:11:33Z")

</div>

Hi @potatoo,  
It sounds like you have the same type of issue as in the link you provided; ultimately, it boils down to having an extraordinary number of unique sequences.

Any chance barcodes are in your reads? Or adapters or primers are still attached to some reads? I recommend making sure you the answer to both of these is "no".

You could also try running through q2-deblur — see the online tutorials for examples. q2-deblur uses a positive filter before attempting to denoise reads, and could help identify if you have unusual amounts of non-target sequences in your data.

Please let us know what you find!

---

<div class="post-metadata">

### Author: ![potatoo](https://forum.qiime2.org/letter_avatar_proxy/v4/letter/p/a87d85/32.png) [@potatoo](https://forum.qiime2.org/u/potatoo)
#### Post date: [October 9, 2019, 4:04pm UTC](https://forum.qiime2.org/t/dada2-execution-halted-error-in-table-attempt-to-make-a-table-with-2-31-elements/11845/3 "2019-10-09T16:04:18Z")

</div>

Thanks for your apply,

Before executed DADA2, I tried to remove adapter and primer using Trimmomatic with custom adapter list collected from FastQC, [illumina adapter sequence](https://support.illumina.com/content/dam/illumina-support/documents/documentation/chemistry_documentation/experiment-design/illumina-adapter-sequences-1000000002694-11.pdf), and [Caporaso et al. (2012)](https://static-content.springer.com/esm/art%3A10.1038%2Fismej.2012.8/MediaObjects/41396_2012_BFismej20128_MOESM81_ESM.txt).

After trimming, these adapters and other technical sequences were less than 0.1 % in all samples.

However, there may be some unknown adapters in samples, as you said. Thus, I will try to use deblur instead and rerun QC pipeline to make sure dataset is adapter-free.

I will update this post, if I find something important.

Thank you for your time and attention.

potatoo

**Reference**  
Caporaso, J. G. et al. Ultra-high-throughput microbial community analysis on the Illumina HiSeq and MiSeq platforms. ISME J. 6, 1621–1624 (2012)

---

<div class="post-metadata">

### Author: ![potatoo](https://forum.qiime2.org/letter_avatar_proxy/v4/letter/p/a87d85/32.png) [@potatoo](https://forum.qiime2.org/u/potatoo)
#### Post date: [October 15, 2019, 1:33pm UTC](https://forum.qiime2.org/t/dada2-execution-halted-error-in-table-attempt-to-make-a-table-with-2-31-elements/11845/4 "2019-10-15T13:33:33Z")

</div>

Hi, @Nicholas_Bokulich,

I have successfully run deblur using the same dataset. Finally, I got 9416 features in 3985 samples which were collected from infants' feces. Total frequency was 77,854,042, and only 40% of joined reads passed through the denoising process (77,864,042 / 194,752,087).

I am not sure about whether these numbers are normal or not. However, the number of features (or unique sequences) seems much lower than the number reported in dada2 error message:

> [@potatoo](#):
>
> **Error in table(pairdf$forward, pairdf$reverse)** :  
> **attempt to make a table with \>= 2^31 elements**  
> **Calls: mergePairs -\> lapply -\> FUN -\> table**  
> **Execution halted**

I am currently checking whether representative sequences contain technical sequences, and trying to find more clues from results generated by deblur. Would you please guide me to solve this problem?

Thank you for your attention and time.

potatoo

### Related files

**deblur execution log:** [deblur.txt](https://forum.qiime2.org/uploads/short-url/p3YR4JhBcQw4vATwgKpsSMjVfhI.txt) (6.1 MB)  
**deblur summary:** [tab\_deno\_16s\_dnmgb\_191015.qzv](https://forum.qiime2.org/uploads/short-url/rwwkC1EQcvSbDKs445SrUDcmj4f.qzv) (898.4 KB)  
**representative sequences:** [rep\_deno\_16s\_dnmgb\_191015.qzv](https://forum.qiime2.org/uploads/short-url/c4RwWHMLeqj32HmScchLzyclS2E.qzv) (1.3 MB)

### Command (joining)

> outdir=/home/qfwfq/DIMP/data/proc/20191007/join\_trim\_16s\_dnmgb\_191007  
> indir=/home/qfwfq/DIMP/data/proc/20190927/qiime\_trim\_16s\_dnmgb\_190927/qiime\_trim\_16s\_HETrim\_190927.qza
> 
> nohup qiime vsearch join-pairs   
> --i-demultiplexed-seqs ${indir}   
> --o-joined-sequences ${outdir}/join\_trim\_16s\_dnmgb\_191007.qza \> ${outdir}/joined\_log\_20191007.txt 2\>&1 &

### Command (deblur)

> indir=/home/qfwfq/DIMP/data/proc/20191007/join\_trim\_16s\_dnmgb\_191007/join\_trim\_16s\_dnmgb\_191007.qza  
> outdir=/home/qfwfq/DIMP/data/proc/20191008/deno\_join\_16s\_dnmgb\_191008
> 
> cd ${outdir}
> 
> nohup qiime deblur denoise-16S   
> --i-demultiplexed-seqs ${indir}   
> --p-trim-length 252   
> --p-sample-stats   
> --o-representative-sequences ${outdir}/rep\_deno\_16s\_dnmgb\_191008.qza   
> --o-table ${outdir}/tab\_deno\_16s\_dnmgb\_191008.qza   
> --o-stats ${outdir}/statstab\_deno\_16s\_dnmgb\_191008.qza \> ${outdir}/deblur\_log\_20191008.txt 2\>&1 &

### Demultiplexed sequence counts summary

| | after trimming adapters | after joining paired-end reads |
| --- | --- | --- |
| Minimum: | 1378 | 162 |
| Median: | 45755.0 | 37178.0 |
| Mean: | 59572.64226623214 | 48822.2830283279 |
| Maximum: | 2557303 | 2173932 |
| Total: | 237635270 | 194752087 |

### Table summary (deblur)

| Metric | Sample |
| --- | --- |
| Number of samples | 3,985 |
| Number of features | 9,416 |
| Total frequency | 77,854,042 |

### Frequency per sample (deblur)

| | Frequency |
| --- | --- |
| Minimum frequency | 2.0 |
| 1st quartile | 6,386.0 |
| Median frequency | 15,014.0 |
| 3rd quartile | 27,612.0 |
| Maximum frequency | 273,337.0 |
| Mean frequency | 19,536.773400250942 |

### Frequency per feature (deblur)

| | Frequency |
| --- | --- |
| Minimum frequency | 10.0 |
| 1st quartile | 16.0 |
| Median frequency | 40.0 |
| 3rd quartile | 220.0 |
| Maximum frequency | 5,107,325.0 |
| Mean frequency | 8,268.271240441802 |

---

<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: [October 15, 2019, 4:22pm UTC](https://forum.qiime2.org/t/dada2-execution-halted-error-in-table-attempt-to-make-a-table-with-2-31-elements/11845/5 "2019-10-15T16:22:25Z")

</div>

> [@potatoo](#):
>
> I have successfully run deblur using the same dataset.

🥳

> [@potatoo](#):
>
> only 40% of joined reads passed through the denoising process (77,864,042 / 194,752,087).

40% joined reads failing to pass is no big surprise, since deblur is somewhat more conservative than dada2 in regards to filtering (deblur denoise-16S performs a "positive filter" to throw out anything that does not look like 16S, then throws out anything that looks like it has an error, whereas dada2 attempts to correct those errors).

> [@potatoo](#):
>
> I got 9416 features in 3985 samples which were collected from infants’ feces.

That does sound a bit high so I wonder if you do have some kind of artifact still in the samples.

> [@potatoo](#):
>
> Before executed DADA2, I tried to remove adapter and primer using Trimmomatic with custom adapter list collected from FastQC, [illumina adapter sequence](https://support.illumina.com/content/dam/illumina-support/documents/documentation/chemistry_documentation/experiment-design/illumina-adapter-sequences-1000000002694-11.pdf), and [Caporaso et al. (2012)](https://static-content.springer.com/esm/art%3A10.1038%2Fismej.2012.8/MediaObjects/41396_2012_BFismej20128_MOESM81_ESM.txt).

Use q2-cutadapt and only trim the _primer sequences_, not the adapter sequences (those will be trimmed out automatically if any primers are discovered).

> [@potatoo](#):
>
> the number of features (or unique sequences) seems much lower than the number reported in dada2 error message

I am not sure if "elements" refers to unique features or # samples \* # features or what — just that it means that dada2 exploded because it is attempting to create an unwieldily large table (usually because barcodes or some other nonsense is included in the reads).

> [@potatoo](#):
>
> –p-trunc-len-f 0  
> –p-trunc-len-r 0

have you tried running dada2 and setting these parameters to some arbitrary value? I don't really have a rational explanation here just a hunch that maybe you are getting noisy, imprecise joins because you have some low-quality bases on the tails of your reads and it is leading to an unusually high number of features with dada2.

Of course the other option is just to use the deblur results... in all honesty dada2 might not yield many more reads and it looks like you have reasonable sample coverage with the deblur results.

---

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### Author: ![potatoo](https://forum.qiime2.org/letter_avatar_proxy/v4/letter/p/a87d85/32.png) [@potatoo](https://forum.qiime2.org/u/potatoo)
#### Post date: [October 16, 2019, 7:27am UTC](https://forum.qiime2.org/t/dada2-execution-halted-error-in-table-attempt-to-make-a-table-with-2-31-elements/11845/6 "2019-10-16T07:27:12Z")

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Thanks for your reply,

In summary, DADA2 create an unusually large table because of unremoved artifacts and low-quality base, resulting in the process suspension.

I will try the following methods to resolve the problem

- Use q2-cutadapt and a reliable list to remove potential artifacts

- Perform quality filtering and trimming before executing DADA2

I will update this post, if I find something important.

Thank you for your time and attention.

potatoo