authCtx.acquireTokenForUser - error: The specified member name is either invalid or empty about csomnode

[vgrem]

Greetings!

That error might happen in case if user was renamed in the local Active directory, follow this article for a possible resolution.

From another hand, since CSOMNode library now supports authentication via app principal credentials you could consider it as alternative option:

var csomapi = require("csom-node");
 
var settings = {
    url: "https://contoso.sharepoint.com/",
    clientId: "YOUR-GUID-GOES-HERE",
    clientSecret: "YOUR-CLIENT-SECRET-GOES-HERE"
};
 
csomapi.setLoaderOptions({url: settings.url});  //set CSOM library settings
 
var authCtx = new AuthenticationContext(settings.url);
authCtx.acquireTokenForApp(settings.clientId, settings.clientSecret, function (err, data) {
    
    var ctx = new SP.ClientContext("/");  //set root web
    authCtx.setAuthenticationCookie(ctx);  //authenticate
    
    //retrieve SP.Web client object
    var web = ctx.get_web();
    ctx.load(web);
    ctx.executeQueryAsync(function () {
        console.log(web.get_title());
    },
    function (sender, args) {
        console.log('An error occured: ' + args.get_message());
    });
      
});