error: uncaughtException: require(...).invokeRolesPolicies is not a function - node.js

Question

I am using MEAN.JS for developing a web app, but for some reason after I made few changes, well mostly copied and paste new modules into the app I see the error as below:
error: uncaughtException: require(...).invokeRolesPolicies is not a function
I dont know why is this happening, anyone has any clue how to fix this?
This is the whole error message:
TypeError: require(...).invokeRolesPolicies is not a function
at C:\oferdo\oferdo\config\lib\express.js:180:39
at Array.forEach (native)
at Object.module.exports.initModulesServerPolicies (C:\oferdo\oferdo\config\lib\express.js:179:32)
at Object.module.exports.init (C:\oferdo\oferdo\config\lib\express.js:252:8)
at C:\oferdo\oferdo\config\lib\app.js:29:23
at C:\oferdo\oferdo\config\lib\mongoose.js:36:15
at C:\oferdo\oferdo\node_modules\mongoose\lib\connection.js:284:19
at open (C:\oferdo\oferdo\node_modules\mongoose\lib\connection.js:511:17)
at C:\oferdo\oferdo\node_modules\mongoose\lib\connection.js:518:7
at C:\oferdo\oferdo\node_modules\mongoose\node_modules\mongodb\lib\db.js:1504:5
at handleCallback (C:\oferdo\oferdo\node_modules\mongoose\node_modules\mongodb\lib\utils.js:96:12)
at _callback (C:\oferdo\oferdo\node_modules\mongoose\node_modules\mongodb\lib\db.js:1420:5)
at C:\oferdo\oferdo\node_modules\mongoose\node_modules\mongodb\lib\db.js:1463:7
at C:\oferdo\oferdo\node_modules\mongoose\node_modules\mongodb\node_modules\mongodb-core\lib\topologies\server.js:1416:5
at finish (C:\oferdo\oferdo\node_modules\mongoose\node_modules\mongodb\node_modules\mongodb-core\lib\auth\scram.js:157:16)
at handleEnd (C:\oferdo\oferdo\node_modules\mongoose\node_modules\mongodb\node_modules\mongodb-core\lib\auth\scram.js:170:7)
at C:\oferdo\oferdo\node_modules\mongoose\node_modules\mongodb\node_modules\mongodb-core\lib\auth\scram.js:264:17
at commandCallback (C:\oferdo\oferdo\node_modules\mongoose\node_modules\mongodb\node_modules\mongodb-core\lib\topologies\server.js:1194:9)
at Callbacks.emit (C:\oferdo\oferdo\node_modules\mongoose\node_modules\mongodb\node_modules\mongodb-core\lib\topologies\server.js:119:3)
at null.messageHandler (C:\oferdo\oferdo\node_modules\mongoose\node_modules\mongodb\node_modules\mongodb-core\lib\topologies\server.js:358:23)
at Socket. (C:\oferdo\oferdo\node_modules\mongoose\node_modules\mongodb\node_modules\mongodb-core\lib\connection\connection.js:292:22)
at emitOne (events.js:77:13)
at Socket.emit (events.js:169:7)
at readableAddChunk (_stream_readable.js:153:18)
at Socket.Readable.push (_stream_readable.js:111:10)
at TCP.onread (net.js:531:20)

Answer 1

Actually, this is nothing to do with incorrectly named files.
You need to make sure that you have the invokeRolesPolicies function defined within your policies file. The minimum required is:
'use strict';
var acl = require('acl');
acl = new acl(new acl.memoryBackend());
exports.invokeRolesPolicies = function () {};
The reason why is that the express.js lib defined in mean.js assumes this is set, and tries to call it, hence the error.

Answer 2

You'll get this error if you have an incorrectly named file under your module's server > policies directory, so check there for any inconsistently named files.
EDIT
I see now that it's not the naming of the file but if you have a file in the policies directory that doesn't contain this method, it will produce this error. In my case I had temporarily commented out the code in a file in this directory in preparation for removal.