Welcome to the forum @Russell_Minton! Glad to hear you are making the transition from Q1 -> Q2 
This error has been reported a few times on the forum, and each time (so far) it seems like windows-style (CRLF) line breaks are the problem. VSEARCH isn't reading these correctly and blows a gasket.
See this topic for an example:
As a first step, use qiime tools validate seqs.qza to check the file.
If that does not turn up anything useful, check out the raw fasta file (i.e., before you import to QIIME 2). Use this command: file seqs.fasta and the output will indicate what type of line endings you have.
If you do have CRLF, use an appropriate command to convert CRLF -> LF line breaks.
Please let us know what you find and if that solves your issue.