# How to find the root cause of a Node error/warning when node-red is starting
**URL:** https://discourse.nodered.org/t/how-to-find-the-root-cause-of-a-node-error-warning-when-node-red-is-starting/6395
**Category:** Developing Nodes
**Created:** [4 January 2019 16:27 UTC](https://discourse.nodered.org/t/how-to-find-the-root-cause-of-a-node-error-warning-when-node-red-is-starting/6395 "2019-01-04T16:27:23Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@germancmartinez](https://discourse.nodered.org/u/germancmartinez)
#### Post date: [4 January 2019 16:27 UTC](https://discourse.nodered.org/t/how-to-find-the-root-cause-of-a-node-error-warning-when-node-red-is-starting/6395/1 "2019-01-04T16:27:23Z")
Hi,
I´m trying to create my own MongoDB connector using the MongoDB node.js driver. To do that I'm creating a node with its corresponding configuration node. I don't get any error when installing my library using npm install but I get an error during the node-red startup. Just to mention, the error is "TypeError: Cannot convert undefined or null to object" and its related to the config node.
**The question is:** Is there any way to know wich is the code line that is generating the error/warning? I´ve no idea where the problem could be and I'm not able to find any debugging tool to find it.
Thanks in advance!
---
### Author:  [@germancmartinez](https://discourse.nodered.org/u/germancmartinez)
#### Post date: [4 January 2019 20:26 UTC](https://discourse.nodered.org/t/how-to-find-the-root-cause-of-a-node-error-warning-when-node-red-is-starting/6395/2 "2019-01-04T20:26:06Z")
This is the log output:
\_4 Jan 17:16:58 - [info]
# Welcome to Node-RED
4 Jan 17:16:58 - [info] Node-RED version: v0.19.5
4 Jan 17:16:58 - [info] Node.js version: v8.9.4
4 Jan 17:16:58 - [info] Windows\_NT 10.0.14393 x64 LE
4 Jan 17:17:00 - [info] Loading palette nodes
4 Jan 17:17:03 - [warn] ------------------------------------------------------
4 Jan 17:17:03 - [warn] [node-red-sherpa/RepositoryConfNode] TypeError: Cannot convert undefined or null to object
4 Jan 17:17:03 - [warn] ------------------------------------------------------
4 Jan 17:17:03 - [info] Settings file : \Users\Administrator.node-red\settings.js
4 Jan 17:17:03 - [info] Context store : 'default' [module=memory]
4 Jan 17:17:03 - [info] User directory : \Users\Administrator.node-red
4 Jan 17:17:03 - [warn] Projects disabled : git command not found
4 Jan 17:17:03 - [info] Flows file : \Users\Administrator.node-red\flows\_WIN-RO73BMGTL4F.json
4 Jan 17:17:03 - [info] Server now running at [http://127.0.0.1:1880/](http://127.0.0.1:1880/)
4 Jan 17:17:03 - [warn]
* * *
Your flow credentials file is encrypted using a system-generated key.
If the system-generated key is lost for any reason, your credentials
file will not be recoverable, you will have to delete it and re-enter
your credentials.
## You should set your own key using the 'credentialSecret' option in your settings file. Node-RED will then re-encrypt your credentials file using your chosen key the next time you deploy a change.
4 Jan 17:17:03 - [info] Starting flows
4 Jan 17:17:03 - [info] Started flows\_
Is there any way of identify the root cause of the problem? The code line number maybe?
---
### Author:  [@BartButenaers](https://discourse.nodered.org/u/BartButenaers)
#### Post date: [4 January 2019 20:54 UTC](https://discourse.nodered.org/t/how-to-find-the-root-cause-of-a-node-error-warning-when-node-red-is-starting/6395/3 "2019-01-04T20:54:27Z")
> [@germancmartinez](#):
>
> The code line number maybe?
Hi @germancmartinez,
Node-RED already contains a piece of code to show the line number, but it doesn't work correctly. I have looked at this in the past, but never solved it. Here is the [information](https://groups.google.com/forum/#!topic/node-red/m3iruVOY3oo), if you want to continue with it...
Would indeed be very useful if it should be fixed!
Bart
---
### Author:  [@knolleary](https://discourse.nodered.org/u/knolleary)
#### Post date: [4 January 2019 22:45 UTC](https://discourse.nodered.org/t/how-to-find-the-root-cause-of-a-node-error-warning-when-node-red-is-starting/6395/4 "2019-01-04T22:45:03Z")
> [@BartButenaers](#):
>
> Node-RED already contains a piece of code to show the line number, but it doesn't work correctly
It does work correctly when node.js provides us a line number to display. If it doesn't give us a number (and there are circumstances where it doesn't) , there's nothing we can do to pluck it out of thin air.
---
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [6 January 2019 03:46 UTC](https://discourse.nodered.org/t/how-to-find-the-root-cause-of-a-node-error-warning-when-node-red-is-starting/6395/5 "2019-01-06T03:46:57Z")
Hi.....
Could I suggest "bombing" the flow with nodes to capture data and put it in a queue?
(eg: [node-red-contrib-queue-gate (node) - Node-RED](https://flows.nodered.org/node/node-red-contrib-queue-gate))
And seeing if "anyone" is sending a null msg.payload? Because:
> [@germancmartinez](#):
>
> [node-red-sherpa/RepositoryConfNode] TypeError: Cannot convert undefined or null to object
Would - to me - imply somewhere there is a naughty msg.payload getting around.
Maybe monitor that part of the flow first and see what happens.
Just a thought.
---
### Author:  [@germancmartinez](https://discourse.nodered.org/u/germancmartinez)
#### Post date: [6 January 2019 04:14 UTC](https://discourse.nodered.org/t/how-to-find-the-root-cause-of-a-node-error-warning-when-node-red-is-starting/6395/6 "2019-01-06T04:14:12Z")
Thanks for your replies. I’ve finally discover where the problem was. My node constructor was declared as async and thats make Node-Red fail.