certificate function host error

Question

certificate function host error

Merrick Fonnesbeck 30

Our certificate for our web application stopped auto-renewing. I looked at out function app that I thought handles the certificate and it was displaying an error about the startup configuration. I am not familiar with what this function does, let alone its configuration problems. I can't seem to upgrade my support subscription in order to get prioritized help from Microsoft. I don't know what to do to get this web site's certificates renewed and functioning again.

The notification errors are:

Error configuring services in an external startup class.
Microsoft.Azure.WebJobs.Script: Error configuring services in an external startup class. AppService.Acmebot: Could not load file or assembly 'Microsoft.Extensions.Configuration.Abstractions, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot find the file specified.

Pashikanti Kumar 1,725 Reputation points Microsoft External Staff Moderator

2025-11-18T19:40:39.7266667+00:00
Hi Merrick Fonnesbeck

Thanks for reaching out on Microsoft Q&A

The error you are encountering indicates that there is an issue with the AppService.Acmebot extension in your Azure Function App, specifically related to a missing or incompatible assembly (Microsoft.Extensions.Configuration.Abstractions, Version=8.0.0.0). This is likely due to a mismatch in dependencies or an update in your Function App runtime or libraries that broke compatibility with Acmebot.

Acmebot is commonly used for automatic SSL/TLS certificate management in Azure App Services. If the certificates stopped auto-renewing and you're seeing this error, it suggests that the Acmebot extension is failing to execute properly.

Update Acmebot to the Latest Version

Acmebot may need an update to support newer runtime versions or dependencies.

Check the official Acmebot GitHub repository for updates: https://github.com/shibayan/AppService.Acmebot

Follow the instructions to update Acmebot in your Function App:

If using Deployment Center, redeploy the latest version of Acmebot.

If using manual installation, update the NuGet package or deployment files.

Reinstall Acmebot

If the issue persists, try reinstalling Acmebot

·         Remove the existing Acmebot deployment from your Function App.

·         Follow the installation instructions from the Acmebot GitHub repository https://github.com/shibayan/AppService.Acmebot

Manually Renew the Certificate

If auto-renewal is failing and the issue is urgent:

·         Navigate to Azure Portal > App Service > TLS/SSL Settings.

·         Check the status of your certificate.

·         If the certificate is expired, manually renew it

Use the App Service Managed Certificate feature to create a new certificate.

Alternatively, upload a custom certificate if available.

Enable Detailed Logging

Enable detailed logging to identify the root cause:

Navigate to Azure Portal > Function App > Monitor > Logs.

Look for specific errors related to Acmebot or dependency loading
Brian Murray 0 Reputation points

2025-11-20T17:26:11.97+00:00

Hi Merrick,

I had the same issue; I've posted a work-around on the appservice-acmebot GitHub site: https://github.com/shibayan/appservice-acmebot/issues/507

Hope this helps!