I'm running the following Pandoc 2.0.3 command on the Mac Terminal command line:
pandoc one.md "metadata.yaml" -o two.pdf
This should take the markdown file one.md and output two.pdf using the yaml file metadata.yaml, a minimal version of which is:
---
header-includes:
- \usepackage{fancyhdr}
...
This Pandoc run produces a PDF as expected for the following version of one.md:
# Report
However, it fails to produce a PDF for the following version of one.md, which contains body text:
# Report
Lorem.
The resulting error message is:
Error producing PDF.
! LaTeX Error: Can be used only in preamble.
See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...
l.65 header-includes: - \usepackage
I don't understand why including that one word creates a failure.