No unmarshaller registered for document element

[Rod Widdowson]

>     metadataFile="/opt/SHIBIDP3/SHIB_SP_26_metadata_file/spmetadata.xml"/>
> ...
>     No unmarshaller registered for document element {urn:mace:shibboleth:2.0:native:sp:config}SPConfig

You need to look at /opt/SHIBIDP3/SHIB_SP_26_metadata_file/spmetadata.xml

My guess is that you accidentally copied shiccoleth2.xml over rather than the metadata.