I faced this problem in my asp.net project with web service. This problem will occur when you are working with web services using ASP.Net. You need to check you app.config file and check the your web service path provided in this app.config file. Just change this path with your existing web service path. You can view your web service path just by right clicking on the web service project and by clicking "View In Browser" option. Just copy path and replace it with the existing wrong path.
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