Marek Skalinski‌, did you ever get this resolved?  If not, how are you setting your variables for the source and destination?  I just posted a working example here. See if that helps. 

I was getting the same error.  I had to add the <m:Fields> node with no elements even though I wasn't passing any additional fields.  I also added the <m:Stream>base64Binary</m:Stream> element to my soap message and mine works fine now.  See below:

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/sharepoint/soap/">
<soap:Header></soap:Header>
<soap:Body>
<m:CopyIntoItems>
<m:SourceUrl>{Common:ItemUrl}</m:SourceUrl>
<m:DestinationUrls>
<m:string>{WorkflowVariable:varDestinationUrl}</m:string>

</m:DestinationUrls>
<m:Fields></m:Fields>
<m:Stream>base64Binary</m:Stream>
</m:CopyIntoItems>
</soap:Body>
</soap:Envelope>

Hi Kevin,

Thanks, how the values of these looks like 

{Common:ItemUrl} :  https://siteurl/Lists/List1/DispForm.aspx?ID=1

{WorkflowVariable:varDestinationUrl} https://siteurl/Lists/List2/

is it correct?

Hi Vijay,

In my case the {Common:ItemUrl} is a link to the actual document and looks like this:

http://sharepointsite/doclibname/document.ext

I also found that I needed to append {ItemProperty:FileLeafRef} to the <m:String> element of the <m:DestinationUrls> node like so:

<m:DestinationUrls>
    <m:string>{WorkflowVariable:varDestinationUrl}{ItemProperty:FileLeafRef}</m:string>

</m:DestinationUrls>

Hope this helps!