Hello,
From what I see from Luke, it seems for Erros we don't use the "message" field instead we use the "error" field - see screenshots.
Also it seems the error field is not indexed, this probably the above query didn't work.
Can you try using : type:errorSnapshot AND SOAP*
I have done a quick test and seems to be working
Example 2: type:errorSnapshot AND "SOAP Fault:(404)Not Found"
Example 3: type:errorSnapshot "mathws.org"
I hope this helps,
Regards,
Sergio