Cannot set xmp property: Bad XML name

[TheBigRed]

I keep getting the following exception just want to know what it means:

com.day.cq.dam.commons.metadata.SimpleXmpToJcrMetadataBuilder Cannot set xmp property: Bad XML name
com.adobe.xmp.XMPException: Bad XML name

Thank you

[smacdonald2008]

What action are you doing when you get this message. Please provide the steps so community can try and reproduce and see if the same results occur. Thanks!! 

[TheBigRed]

There's a custom workflow involved in writing properties to an asset's metadata node. We

left some properties blank as we have a use case for editors to come in and fill them later.

Also there are two or three properties that don't follow any metadata standard but we have it there for personal use.

Thanks!

[Amit_Kumar]

Can you post your workflow model code here?

[Sham_HC]

does three custom property name contain any namespace?  If so create that namespace,