This is an informational maybe-bug, I was not able to reproduce it. One of my novice contributors ran into it but resolved it on their own. Perhaps this report will be helpful.

They received the following error, and there was legitimately something wrong with the directive. But it wasn't on "line 1, column 1" as the message stated. It was several lines into the document and indented.

WARNING: Directive 'image': Invalid options YAML: while parsing a block mapping
 in "<unicode string>", line 1, column 1:
  width: 650px
  ^

I was expecting it to say "line 10, column 4" or whatever.

The md file contained something approximately like this. (I was not able to inspect the broken file.) The problem line, or perhaps something nearby, may have contained unexpected whitespace (like a tab?)

## some heading

1. some list item

   '''{image} image.png
       :width: 650px
       :alt: image description
       '''

Environment:

MacOS, probably Catalina

requirements.txt:

sphinx==3.4.0
six>=1.10.0
sphinxcontrib.mermaid>=0.5.0
myst-parser==0.13.3
furo==2021.02.21.beta25
sphinx-copybutton>=0.3.1
sphinx-inline-tabs==2020.10.19b4