Empty reply from server

[GuohuaZhu]

when I used the function extract_outcome_data, in for cycle to extract a immune cell GWAS dataset. It went error at the 50th cycle.
It shows as follows:

immu.cell.outcome <- list()
for (x in 1:length(immunecell.id)) {
  repeat{
    try({immu.cell <- extract_outcome_data(snps = exp.1e.06$SNP,outcomes = immunecell.id[x])})
    if(exists("immu.cell")){break}
    Sys.sleep(0.5)
  }
  immu.cell.outcome <- list.append(immu.cell.outcome,immu.cell)
  rm(immu.cell)
  print(str_c(x," has been processed !"))
}
……
Extracting data for 8 SNP(s) from 1 GWAS(s)
Finding proxies for 7 SNPs in outcome ebi-a-GCST90001440
Extracting data for 7 SNP(s) from 1 GWAS(s)
[1] "50 has been processed !"
Extracting data for 8 SNP(s) from 1 GWAS(s)
Error in api_query("associations", query = list(variant = variants, id = id,  : 
  The following error was encountered in trying to query the MR-Base server:
Error in curl::curl_fetch_memory(url, handle = handle): Empty reply from server

Extracting data for 8 SNP(s) from 1 GWAS(s)
Error in api_query("associations", query = list(variant = variants, id = id,  : 
  The following error was encountered in trying to query the MR-Base server:
Error in curl::curl_fetch_memory(url, handle = handle): Empty reply from server

Extracting data for 8 SNP(s) from 1 GWAS(s)
Error in api_query("associations", query = list(variant = variants, id = id,  : 
  The following error was encountered in trying to query the MR-Base server:
Error in curl::curl_fetch_memory(url, handle = handle): Empty reply from server

Extracting data for 8 SNP(s) from 1 GWAS(s)

How to solve this.