Intermittent Error "Worker was unable to load function modelEventProcessor: 'Cannot find module 'main.js'"

Steven Fafel 0

Hi All!

I have a Node.js Azure Function. On August 28, 2024 (or about that) we started seeing an error when Azure Functions were starting. We don't see anything in particular that we night have done to cause it - no major code changes - and it's happening in our Production and Test environments. And it doesn't seem to be related to load. And to be clear - it is intermittent - sometimes it starts fine. We SUSPECT that it might have something to do that we're on the Consumption Model. Here is the full error:

Exception: Worker was unable to load function modelEventProcessor: 'Cannot find module 'main.js' Require stack: - /azure-functions-host/workers/node/dist/src/worker-bundle.js - /azure-functions-host/workers/node/dist/src/nodejsWorker.js' Stack: Error: Worker was unable to load function modelEventProcessor: 'Cannot find module 'main.js' Require stack: - /azure-functions-host/workers/node/dist/src/worker-bundle.js - /azure-functions-host/workers/node/dist/src/nodejsWorker.js' at Module._resolveFilename (node:internal/modules/cjs/loader:1140:15) at Module._load (node:internal/modules/cjs/loader:981:27) at Module.require (node:internal/modules/cjs/loader:1231:19) at Object.apply (/azure-functions-host/workers/node/dist/src/worker-bundle.js:2:51713) at require (node:internal/modules/helpers:177:18) at /azure-functions-host/workers/node/dist/src/worker-bundle.js:2:49326 at Generator.next (

Steven Fafel 0 Reputation points

2024-09-12T23:03:05.65+00:00

Additional note: We are using a single storage account for all of our 33 Azure Functions...it was recommended to us that we create storage accounts per Azure Function. Could this be a solution?
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Ryan Hill 28,631 Reputation points Microsoft Employee

2024-09-13T20:54:47.0033333+00:00

It's difficult to say @Steven Fafel. Furthermore, a shared storage account shouldn't be an issue unless something weird is being done with host id or content sharing. Could be something else, but we'll need get more details. Is it one function app or different ones that are intermittent?
Steven Fafel 0 Reputation points

2024-09-13T23:53:39.47+00:00

Hi Ryan! Thank you so much for weighing in here. It is extremely bizarre. Prior to August 28th, we didn't have any chronic issues at all across 30+ azure functions. All of a sudden on August 28th, across many of our functions, they intermittently won't start. Is there any way that you can help?
Steven Fafel 0 Reputation points

2024-09-13T23:56:30.7466667+00:00

Another note. There were no code changes made across all of our functions, but they just started to get the error when loading on August 28th.
Steven Fafel 0 Reputation points

2024-09-14T00:03:09.4066667+00:00

Ryan - here is a chart of our function errors over the past month or so. You can see we had no issues prior to August 28th.
Steven Fafel 0 Reputation points

2024-09-16T14:04:26.7033333+00:00

Ryan - we are using the instructions in this article to "Run from Package". https://video2.skills-academy.com/en-us/azure/azure-functions/run-functions-from-deployment-package

This seems to be helping.....but is there any answer why things might have changed on August 28.....OR....perhaps on the Consumption Model we hit some limit?
Ryan Hill 28,631 Reputation points Microsoft Employee

2024-09-17T00:31:45.01+00:00

@Steven Fafel have you ran any of the Diagnose and solve problems blade tools around availability and performance? Just to confirm, we're talking about 30 different functions within a single app that's on consumption plan correct?
Steven Fafel 0 Reputation points

2024-09-17T14:12:13.14+00:00
Hi Ryan! Yes, we have. Something we did yesterday....we moved our functions to load from a Package file (https://video2.skills-academy.com/en-us/azure/azure-functions/run-functions-from-deployment-package) and this seems to have drastically improved things.

If this resolves the issue, why would it have suddenly started on August 28th?

Was there something on the MS side that might have changed to cause this?

We have not changed any code....but just are now loading it from a package....why is this so different?

We are hoping it's resolved...but would really love to know what happened to cause this.
Ryan Hill 28,631 Reputation points Microsoft Employee

2024-09-18T02:24:42.7866667+00:00

Hey @Steven Fafel can you respond to the private message so I can get some additional details from you?
Steven Fafel 0 Reputation points

2024-09-18T14:20:00.44+00:00

Hi Ryan! Sure - but what private message? I am not sure I am seeing one.
Ryan Hill 28,631 Reputation points Microsoft Employee

2024-09-24T13:00:44.6266667+00:00

@Steven Fafel you should see Private Message button next to Report a concern under the question post.

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Intermittent Error "Worker was unable to load function modelEventProcessor: 'Cannot find module 'main.js'"

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