Capturing traces may cause loss of monitoring of target process in .NET Monitor 7.1.0 and 8.0 Preview 2

[jander-msft]

Issue

When capturing traces via the /trace HTTP route or through the CollectTrace collection rule action, the .NET Monitor tool may stop observing the target process at the end of the trace collection. You will likely see a message such as Unexpected timeout from process #. Process will no longer be monitored. If collection rules are configured for that process, the .NET Monitor tool may no longer monitor that process and you will see the Stopping collection rules. message. The process will not be available for collecting diagnostic artifacts, for running collection rules, or for querying for process information until the .NET Monitor tool is restarted.

See #3916 for more details.

Impacted versions

• 7.1.0
• 8.0 Preview 2

The 6.X versions are NOT impacted by this issue.

Workarounds

There are no workarounds for the behavior for the specified versions at this time.

If you are impacted by this issue, it is advised that you pin the installation of .NET Monitor until a servicing update is released with the fix.

Docker Images

For the 7.x Docker images, use a major-minor version tag e.g. 7.0-alpine, 7.0-cbl-mariner instead of the major-only version e.g. 7-alpine, 7-cbl-mariner as would normally be recommended.

# Get the latest 7.0.X patch version
docker pull mcr.microsoft.com/dotnet/monitor:7.0
docker run mcr.microsoft.com/dotnet/monitor:7.0

For the 8.x Docker images, use the Preview 1 tags e.g. 8.0.0-preview.1-ubuntu-chiseled, 8.0.0-preview.1-cbl-mariner-distroless instead of the floating preview tags e.g. 8.0-preview-ubuntu-chiseled, 8.0-preview-cbl-mariner-distroless as would normally be recommended.

docker run mcr.microsoft.com/dotnet/monitor:8.0.0-preview.1

The fix for the issue has already been made and is available in the dotnet nightly MCR repository at mcr.microsoft.com/dotnet/nightly/monitor. Images from this repository are of a daily build quality and may have other issues or incomplete features.

.NET Tool

For the 7.x tool, install:

dotnet tool install -g dotnet-monitor --version 7.0.*

or update:

dotnet tool update -g dotnet-monitor --version 7.0.*

to get the latest 7.0.X version.

For the 8.x tool, use Preview 1:

dotnet tool install -g dotnet-monitor --version 8.0.0-preview.1*

If you've already updated your .NET Tool installation, uninstall it and reinstall one of the above versions.

dotnet tool uninstall -g dotnet-monitor

Follow-up

We will update this announcement if more information becomes available and when the fix for the issue has been shipped.

[jander-msft]

This issue has been fixed in the 8.0 Preview and 7.1.1 releases.