Hello there community!

I have been trying to use biomaRt recently and so far I got it working and it was fantastic. Today, I don't know the reasons, I get these kind of errors again and again.

Error: biomaRt has encountered an unexpected server error.
Consider trying one of the Ensembl mirrors (for more details look at ?useEnsembl). 

I have tried to connect to other mirrors, "www", "useast", "uswest"... but none of them work.

Using different functions within biomaRt I always get the same, and sometimes it just works but its very annoying. Here are some of the examples of what I mean:

> listMarts()
Error in bmRequest(request = request, verbose = verbose) : 
  Internal Server Error (HTTP 500).

> ensembl_mm = useDataset("mmusculus_gene_ensembl",mart=ensembl_mm)
Error in bmRequest(request = request, verbose = verbose) : 
  Internal Server Error (HTTP 500).

> datasets <- listDatasets(ensembl_mm)
Error in bmRequest(request = request, verbose = verbose) : 
  Internal Server Error (HTTP 500).

> ensembl_df <- getBM (attributes = c("ensembl_gene_id", "description", "chromosome_name", "mgi_description", "mgi_symbol", "mgi_id", "go_id", "definition_1006"), mart = ensembl_mm)
Error: biomaRt has encountered an unexpected server error.
Consider trying one of the Ensembl mirrors (for more details look at ?useEnsembl)

Also attaching sessioninfo():

> sessionInfo()
R version 3.6.3 (2020-02-29)
Platform: x86_64-apple-darwin15.6.0 (64-bit)
Running under: macOS Mojave 10.14.6
Matrix products: default
BLAS:   /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRlapack.dylib
locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     
other attached packages:
[1] biomaRt_2.42.1
loaded via a namespace (and not attached):
 [1] Rcpp_1.0.4           pillar_1.4.3         compiler_3.6.3       dbplyr_1.4.2         prettyunits_1.1.1   
 [6] tools_3.6.3          progress_1.2.2       digest_0.6.25        bit_1.1-15.2         RSQLite_2.2.0       
[11] memoise_1.1.0        BiocFileCache_1.10.2 tibble_3.0.0         lifecycle_0.2.0      pkgconfig_2.0.3     
[16] rlang_0.4.5          cli_2.0.2            DBI_1.1.0            rstudioapi_0.11      curl_4.3            
[21] parallel_3.6.3       stringr_1.4.0        httr_1.4.1           dplyr_0.8.5          rappdirs_0.3.1      
[26] S4Vectors_0.24.3     vctrs_0.2.4          askpass_1.1          IRanges_2.20.2       hms_0.5.3           
[31] tidyselect_1.0.0     stats4_3.6.3         bit64_0.9-7          glue_1.3.2           Biobase_2.46.0      
[36] R6_2.4.1             fansi_0.4.1          AnnotationDbi_1.48.0 XML_3.99-0.3         purrr_0.3.3         
[41] blob_1.2.1           magrittr_1.5         ellipsis_0.3.0       BiocGenerics_0.32.0  assertthat_0.2.1    
[46] stringi_1.4.6        openssl_1.4.1        crayon_1.3.4        
> 

Sincerely,

Javi.

If the mirror fix doesn't work, I recommend the following function:

library(dplyr)
mouse_human_genes = read.csv("http://www.informatics.jax.org/downloads/reports/HOM_MouseHumanSequence.rpt",sep="\t")

convert_mouse_to_human <- function(gene_list){

  output = c()

  for(gene in gene_list){
    class_key = (mouse_human_genes %>% filter(Symbol == gene & Common.Organism.Name=="mouse, laboratory"))[['DB.Class.Key']]
    if(!identical(class_key, integer(0)) ){
      human_genes = (mouse_human_genes %>% filter(DB.Class.Key == class_key & Common.Organism.Name=="human"))[,"Symbol"]
      for(human_gene in human_genes){
        output = append(output,human_gene)
      }
    }
  }

  return (output)
}

Please either highlight your blocks of code and then click the 101010 button or put a triple backtick (the top left key on a QWERTY keyboard) before and after. Otherwise people have to fix your post to make it legible (like I just did).

It has been pointed out recently (many times) by Mike Smith that the main ensembl servers are being upgraded, and that using a mirror is the way to go. Which works for me:

> library(biomaRt)
> mart <- useEnsembl("ensembl","mmusculus_gene_ensembl", mirror = "useast")
> getBM(c("ensembl_gene_id", "description", "chromosome_name", "mgi_description", "mgi_symbol", "mgi_id", "go_id", "definition_1006"), "ensembl_gene_id","ENSMUSG00000041147", mart)
> dim(z)
[1] 62  8

You say you used different mirrors, but the code you post doesn't indicate that you did so. You should try that. And do note that pretty much any online data source is prone to connection issues, and sometimes you just have to wait a bit and try again.