Do you see this error while testing web service from SICF (Transaction Code)?

For me a small change in SOAMANAGER solved this error, go to SOAMANAGER --> Web Service Configuration

Search for your web service

Select this Web Service --> Click on Pencil Icon

Go to Transport Settings Tab :

Option : Make Local Call --> From drop down select

No make a Test again in Tcode - SICF, you will not see the error again, there will be a blank page. There may be other reason too but for me, it worked. My system information:

I hope it will help someone to get rid of this error.
Kind Regards
Manna Das