Web deployment task failed. (Unable to write data to the transport connection: An established connection was aborted by the software in your host machine.)

Question

For the past three days almost all of my deploy efforts fail with a message similar to:
Web deployment task failed. (Unable to write data to the transport connection: An established connection was aborted by the software in your host machine.)

If it does finally go through I get an assembly binding error that appears to be from some of the files not actually making it to the server.
I have reinstalled Visual Studio. Redownloaded the repos. At a loss as to what to do now.

Answer 1

Hi Ken Ilari

Thank you for posting your question on Microsoft Q&A.

From your description, it seems that you are experiencing deployment failures with the error: “Web deployment task failed. (Unable to write data to the transport connection: An established connection was aborted by the software in your host machine.)”

You also mentioned that in some cases the deployment eventually succeeds, but certain assemblies are missing, which results in binding errors.

This behavior can often occur if firewall or antivirus software is interfering with the connection required for deployment. Please ensure that Visual Studio is allowed through your firewall and antivirus by adding the necessary exceptions.

Additionally, if you are deploying to Azure App Service, I recommend reviewing the Kudu logs for more detailed information. You can access Kudu by following these steps:

1. Navigate to your App Service in the Azure Portal.
2. Under Development Tools, select Advanced Tools and then click Go.
3. This will open the Kudu console in a new tab where you can explore logs under the Debug Console -> CMD/Powershell -> LogFiles folder (for example, LogFiles\kudu\trace).

Based on the information in those logs, here are some possible solutions you can try:

• Check file size limits – Large files may fail during deployment. If related errors appear, consider increasing maxAllowedContentLength in Web.Config or splitting large files.
• Check disk quota – If the App Service plan has reached its storage quota, deployments can fail. Logs will show “No space left” or similar. Free up space or scale the plan.
• Try alternate deployment methods – If using Visual Studio publish, test once with ZipDeploy or Azure DevOps/GitHub Actions to confirm if the issue is specific to one method.
• Enable detailed error messages – In web.config, set customErrors mode="Off" and aspNetCore stdoutLogEnabled="true". You can then check detailed logs in LogFiles.
• Restart or scale the App Service – Restarting sometimes clears stuck processes. If issues persist, temporarily scale up the App Service plan and redeploy.

To better assist you, could you please confirm:

Which deployment method you are using (Visual Studio, VS Code extension, GitHub Actions, Azure DevOps, etc.)?

Were you able to successfully deploy the same code to this Web App previously, or is this the first time you are seeing this error?

For additional guidance, you may also refer to the official documentation here: Troubleshoot ASP.NET Core on Azure App Service and IIS.

Please feel free to share back with the above details, and the community will be glad to help you further.