"Adaptor or bad ligation of read X" report

[crysclitheroe]

Dear fastp Developers

Thank you for sharing this excellent software it's incredibly useful! I am currently doing some quality checking of a large dataset of libraries, and am encountering the above report for the first time. Usually Im used to seeing some Adaptor reported, but not this.

Sometimes its just for read 2, sometimes for both reads.

Can you suggest most likely/possible causes of this? Is it a sequencing error (reads not reading correctly or fragments not binding to the flowcell) or library prep error, i.e expired enzyme or low concentration primers or multiple primer sets?

Any insight would be much appreciated. Thanks and kind regards Crystal

[bwprice]

same here - any ideas what causes this? hello Crystal :)