Hi everyone
recently I download some SRA files (12 files) using this command from NCBI:


    prefetch ERR4172779

all of SRA file were dowloaded properly but when I try to convert them to fastq files using this command : 

    fastq-dump --split-3  ERR4172779

 , it shows this:





    2020-08-12T11:42:02 fastq-dump.2.9.4 err: file invalid while opening directory within file system module - failed to resolve column 'READ' idx '1'
    
    2020-08-12T11:42:02 fastq-dump.2.9.4 err: file invalid while opening directory within file system module - failed to resolve column 'READ' idx '1'
    
    2020-08-12T11:42:02 fastq-dump.2.9.4 err: file invalid while opening directory within file system module - failed ERR4172779.sra
    
    ==================================================
    
    An error occurred during processing.
    A report was generated into the file '/home/mohammad/ncbi_error_report.xml'.
    If the problem persists, you may consider sending the file
    to 'sra-tools@ncbi.nlm.nih.gov' for assistance.




what's the problem??









Looking at the ENA archive [here](https://www.ebi.ac.uk/ena/browser/view/ERR4172779), it seems fastq files are not available for this accession. However, they provide BAM files.

(As a side note, in my opinion is better to work with ENA than SRA, see also this answer of mine at https://bioinformatics.stackexchange.com/a/14121/339) 