Joyce, It seems to be related to the UCSC BSgenome package you installed. You might want to update it. This post might be helpful to you. problems in installing BSgenome.Mmusculus.UCSC.mm10 Best, Julie Activity on a post you are following on support.bioconductor.org<https: support.bioconductor.org=""> User joyce<https: support.bioconductor.org="" u="" 14189=""/> wrote Question: CRISPRseek offTargetAnalysis error<https: support.bioconductor.org="" p="" 104167=""/>: Hi Julie, I am running offTargetAnalysis to find gRNAs and their off-targets in some sequences. For a couple of sequences, I got the following error message while the program is trying to find all hits in a particular sequence: "Error in .seqlengths_TwoBitFile(x) : UCSC library operation failed Calls: offTargetAnalysis ... seqinfo -> seqinfo -> .seqlengths_TwoBitFile -> .Call In addition: Warning message: In .seqlengths_TwoBitFile(x) : End of file reading 4 bytes" Could you please tell me what the cause of this error message may be? Thanks, Joyce ________________________________ Post tags: crisprseek You may reply via email or visit CRISPRseek offTargetAnalysis error