This error appears to be a custom error, not an actual error message. If it is an error caused by uploading a too large file, I think it may be a problem with the server configuration. In my experience, you need to include the following configuration.
<bindings>
<basicHttpsBinding>
<binding name="mybinding" maxReceivedMessageSize="2147483647">
</binding>
</basicHttpsBinding>
</bindings>
Then apply it in the particular service endpoint.
<services>
<service name="WcfService1.Service1">
<endpoint bindingConfiguration="mybinding" address="" binding="basicHttpBinding" contract="WcfService1.IService1"></endpoint>
</service>
</services>
At last, I would like to know the practical error if the problem still exists. Feel free to let me know if there is anything I can help with.