Hi, I have been processing files for data imputation using Michigan Imputation Server. When I have done this previously, the imputation worked. Just recently I prepared my files as usual and now when I submit my zipped files, I get this error:

"Unable to parse header with error: null, for input source: /data3/imputation-server/workspace/job"

I cannot see what I have done differently. I assumed this had something to do with the header on my vcf file, but this is no different than before.

Does this error look familiar? If so, how should I fix my files?

Thank you.