Just found out that QGis 3.x has a metadata editor. That is great! Is there a tool to convert the metadata saved by QGIS (.qmd file) to a ISO-xml standard metadata file?
Why am I asking this: I though of using QGis to create the xml metadata file that we will use to populate a Metadata Catalog
Best Answer
Not 100% on this but I think metadata is a work in progress, being approached from a number of angles.
If you have metadata to save, apparently it can be saved to a file which sits in the same directory as the data. As per this answer QGIS Default Metadata
If you are trying to read existing metadata from another system (your case) I presume QGIS is expecting to read a *.qmd file.
There is a plugin which apparently used to help some users, but apparently it no longer works with updated version of QGIS. https://github.com/nextgis/metatools/issues