I have problem with REST Query that should update field in project. I am sending the following Query:

var projectItem = {     "projectId":  "21dba5cc-43e9-e611-80e2-02bf0a010149",     "propertyId": '22301607-98b8-e611-80e6-02bf0a010149',     "value": "Some example Action field value." };  var projectUpdated = false; jQuery.ajax({     url: _spPageContextInfo.siteAbsoluteUrl + '/_api/ProjectServer/WorkflowActivities/updateTextProperty',     type: 'POST',     contentType: 'application/json;odata=verbose',     data: JSON.stringify(projectItem),     headers: {         "Accept": 'application/json;odata=verbose',         "X-RequestDigest": jQuery('#__REQUESTDIGEST').val()     },     success: function(data) {         console.log("jQuery ajax was finished successfully with the following prop: ");         console.log("    Project id: " + projectItem.projectId + ",");          console.log("    Field id: " + projectItem.value);         console.log("    Field value: " + projectItem.value);     },     error: function(data) {         console.log("jQuery ajax was finished unsuccessfully with the following error:");         console.log("    data.status: " + data.status);         console.log("    data.statusText: " + data.statusText);         console.log("    data.responseText: " + data.responseText);     } }); 

And I get the following error:

jQuery ajax was finished unsuccessfully with ther following error:     data.status: 403     data.statusText: FORBIDDEN     data.responseText: {"error":{"code":"-2130575252, Microsoft.SharePoint.SPException","message":{"lang":"en-US","value":"The security validation for this page is invalid and might be corrupted. Please use your web browser's Back button to try your operation again."}}}