How can I get Managed Metadata column values from sub sites by using rest API in SharePoint hosted app?

Question

I have used two method to achieve my goal:

var REQUESTEXECUTOR = new SP.RequestExecutor(APPWEBURL);

REQUESTEXECUTOR.executeAsync({

        url: _ihda.appWebURL + "/_api/sp.appcontextsite(@target)/web/Lists/GetByTitle('Projects Info')/GetItems(query=@v1)?@v1={'ViewXml':'<View><Query></Query></View>'}&@target='" + projectPath + "'",

        type: "POST",

        headers: {
            "accept": "application/json;odata=verbose",
            "content-type": "application/json;odata=verbose",
            "X-RequestDigest": $("#__REQUESTDIGEST").val()

        },

success: function (data) {

            success(JSON.parse(data.body));

        },
        error: function (data) {

        }

This code return us error {"code":"-1, Microsoft.SharePoint.Client.ClientServiceException","message":{"lang":"en-US","value":"The HTTP method 'GET' cannot be used to access the resource 'GetItems'. The operation type of the resource is specified as 'Default'. Please use correct HTTP method to invoke the resource."

In alternative solution when I run using the TaxCatchAll field

http://prj/Projects/11181/_api/web/Lists/GetByTitle('Projects%20Info')/Items?$select=*,$expand=TaxCatchAll

then, this code return us error: The expression "*,$expand=TaxCatchAll" is not valid for subsite.