Aspire CLI: Markdown errors

[lvde0]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I have a custom publisher that logs some debug info via ILogger<T>.LogDebug("{x}, "<some json here>"). When I run aspire deploy I receive the following error:

An unexpected error occurred: Unbalanced markup stack. Did you forget to close a
[2026-01-06T15:30:03.837Z] tag?

Expected Behavior

User arguments passed to the logger should be properly escaped to prevent markdown errors.

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version info

10.0.101

Anything else?

No response

[MihuBot]

I'm a bot. Here is a possible related and/or duplicate issue (I may be wrong):

• CLI does not properly escape markup tags #11294

[lvde0]

Narrowed down the issue to \n and \r\n characters... It seems to choke the whole logger even when using Markup.Escape()

[OwenR98]

Also having a similar issue on deployment of a Function App, when incorrectly configured the "Bad Request" response returns and then errors in the console before displaying the error reason.

11:13:18 (provision-functions-website) ✗ Failed to provision functions-website: Deployment failed: BadRequest: { 11:13:18 (provision-functions-website) ✗ "Code": "BadRequest", ❌ An unexpected error occurred: Unbalanced markup stack. Did you forget to close a tag?

[kamranayub]

Running into this too, when redirecting output for az command and trying to print out debug info during pipeline step:

static async Task<string> RunAzCliCommand(PipelineStepContext ctx, params string[] args)
    {
        using var azProcess = Process.Start(CreateAzStartInfo(args)) ?? throw new InvalidOperationException("Failed to start az CLI process");

        ctx.Logger.LogDebug("Launching process: {Process} {Args}", azProcess.StartInfo.FileName, string.Join(" ", azProcess.StartInfo.ArgumentList));

        var stdoutTask = azProcess.StandardOutput.ReadToEndAsync(ctx.CancellationToken);
        var stderrTask = azProcess.StandardError.ReadToEndAsync(ctx.CancellationToken);

        await azProcess.WaitForExitAsync(ctx.CancellationToken).ConfigureAwait(false);

        var stdout = await stdoutTask.ConfigureAwait(false);
        var stderr = await stderrTask.ConfigureAwait(false);

        ctx.Logger.LogDebug("Az CLI STDOUT: {StdOut}", stdout);
        ctx.Logger.LogDebug("Az CLI STDERR: {StdErr}", stderr);

        if (azProcess.ExitCode != 0)
        {
            throw new InvalidOperationException(
                $"az CLI process exited with code {azProcess.ExitCode}\nSTDOUT: {stdout}\nSTDERR: {stderr}");
        }    

        return stdout.Trim();
    }

Chokes on LogDebug for stdout and stderr!

Workaround

Since stdout/stderr can be multiple lines, I split and then log each line individually for debugging.