I am trying to perform differential analysis on gene data but I am struggling to solve the following error. After creating the DESeqDataSet object with DESeq() function I am trying to get the result tables by using the result() function on the DESeqDataSet object ds generated as follows:

results( ds, contrast = c("clinical_group", "Treatment", "Control") )

but I am getting an error

'Error in .wrap_in_length_one_list_like_object(value, name, x) : 
  failed to coerce 'list(value)' to a DESeqResults object of length 1'

Any ideas? I am using DESeq2 version 1.20.0

My sessionInfo()

> sessionInfo()
R version 3.6.2 (2019-12-12)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows >= 8 x64 (build 9200)

Matrix products: default

locale:
[1] LC_COLLATE=Spanish_Spain.1252  LC_CTYPE=Spanish_Spain.1252    LC_MONETARY=Spanish_Spain.1252
[4] LC_NUMERIC=C                   LC_TIME=Spanish_Spain.1252    

attached base packages:
[1] parallel  stats4    stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
 [1] DESeq2_1.20.0               SummarizedExperiment_1.16.1 DelayedArray_0.12.2        
 [4] BiocParallel_1.20.1         matrixStats_0.55.0          Biobase_2.46.0             
 [7] GenomicRanges_1.38.0        GenomeInfoDb_1.22.0         IRanges_2.20.2             
[10] S4Vectors_0.24.3            BiocGenerics_0.32.0        

loaded via a namespace (and not attached):
 [1] bit64_0.9-7            splines_3.6.2          Formula_1.2-3          assertthat_0.2.1      
 [5] latticeExtra_0.6-29    blob_1.2.1             GenomeInfoDbData_1.2.2 yaml_2.2.1            
 [9] pillar_1.4.3           RSQLite_2.2.0          backports_1.1.5        lattice_0.20-38       
[13] glue_1.3.1             digest_0.6.24          RColorBrewer_1.1-2     XVector_0.26.0        
[17] checkmate_2.0.0        colorspace_1.4-1       htmltools_0.4.0        Matrix_1.2-18         
[21] XML_3.99-0.3           pkgconfig_2.0.3        genefilter_1.68.0      zlibbioc_1.32.0       
[25] purrr_0.3.3            xtable_1.8-4           scales_1.1.0           jpeg_0.1-8.1          
[29] htmlTable_1.13.3       tibble_2.1.3           annotate_1.64.0        ggplot2_3.2.1         
[33] nnet_7.3-12            lazyeval_0.2.2         survival_3.1-8         magrittr_1.5          
[37] crayon_1.3.4           memoise_1.1.0          foreign_0.8-75         tools_3.6.2           
[41] data.table_1.12.8      lifecycle_0.1.0        stringr_1.4.0          locfit_1.5-9.1        
[45] munsell_0.5.0          cluster_2.1.0          AnnotationDbi_1.48.0   compiler_3.6.2        
[49] rlang_0.4.4            grid_3.6.2             RCurl_1.98-1.1         rstudioapi_0.11       
[53] htmlwidgets_1.5.1      bitops_1.0-6           base64enc_0.1-3        gtable_0.3.0          
[57] DBI_1.1.0              R6_2.4.1               gridExtra_2.3          knitr_1.28            
[61] dplyr_0.8.4            bit_1.1-15.2           Hmisc_4.3-1            stringi_1.4.6         
[65] Rcpp_1.0.3             geneplotter_1.64.0     vctrs_0.2.3            rpart_4.1-15          
[69] acepack_1.4.1          png_0.1-7              tidyselect_1.0.0       xfun_0.12

Reproducible example:

> cnts <- matrix(rnbinom(n=1000, mu=100, size=1/0.5), ncol=10)
> cond <- factor(rep(1:2, each=5))
> dds <- DESeqDataSetFromMatrix(cnts, DataFrame(cond), ~ cond)
converting counts to integer mode
> dds <- DESeq(dds)
estimating size factors
estimating dispersions
gene-wise dispersion estimates
mean-dispersion relationship
-- note: fitType='parametric', but the dispersion trend was not well captured by the
   function: y = a/x + b, and a local regression fit was automatically substituted.
   specify fitType='local' or 'mean' to avoid this message next time.
final dispersion estimates
fitting model and testing
> res <- results(dds)
Error in .wrap_in_length_one_list_like_object(value, name, x) : 
  failed to coerce 'list(value)' to a DESeqResults object of length 1

I don't get an error with your code.

> res <- results(dds)

Looking into your sessionInfo, you have DESeq2_1.20.0 (not a problem per se, but note that this is 3 releases too old, if you are starting a new project it would be recommended to use current software).

However, it is a problem that you have paired DESeq2 1.20 with R version 3.6.2. This version should be paired with R version 3.5.0.

Make sure that you only use BiocManager::install() to install packages. Going off that script will result in problems which are out of our hands as developers. You can consult BiocManager::valid() to diagnose problems on your end.