RagTag error: "OSError: error when opening file"

[ylzou867]

I am running RagTag to scaffold an assembly.
It runs fine, makes the log file and part of the output, but at the last step gives an error:

Traceback (most recent call last):
File "/home/zyl/miniforge3/bin/ragtag_patch.py", line 518, in
main()
File "/home/zyl/miniforge3/bin/ragtag_patch.py", line 353, in main
ref_fai = pysam.FastaFile(reference_ctg_fn)
File "pysam/libcfaidx.pyx", line 121, in pysam.libcfaidx.FastaFile.cinit
File "pysam/libcfaidx.pyx", line 181, in pysam.libcfaidx.FastaFile._open
OSError: error when opening file /home/zyl/ragtag/Mjof/ragtag_output/ragtag.patch.ctg.fasta