ema align core dumped

[MaestSi]

Hi, I tried to use the ema align command to have barcoded reads aligned to a reference. However I got this error:

BWA initialization... [M::bwa_idx_load_from_disk] read 0 ALT contigs Processing reads... ema: src/techs.c:8: extract_bc_10x: Assertion `bc_str != NULL' failed. Aborted (core dumped)

Since ema preproc didn't produce any "special fastq" file, I am not specifying the -s parameter. I read another user (Issue #15 ) had this error and solved it with: cat reads.fastq | paste - - - - - - - - | grep "BX:Z:" | tr '\t' '\n' > reads_noBXZ.fastq However, the files I got are empty. Do you know how could I solve this? Simone