This document does not apply to Azure Function hosts. For Azure Function hosts, see Azure Function Isolated Worker diagnostics.
To make troubleshooting easier, diagnostic information is collected during endpoint startup and written to a . sub-folder in the host output directory.
By default, the output directory is called AppDomain., except for web applications where App_Data is used instead.
To change the output path:
endpointConfiguration.SetDiagnosticsPath("myCustomPath");
At every endpoint startup the current diagnostics will be written to {endpointName}-configuration.. If possible, attach this file to support requests.
The structure and format of the data produced should not be considered stable or parsable. Nodes may be added, removed, or moved in minor and patch versions.
Sample content
Sample partial content of the startup diagnostics (formatted for readability):
{
"Container": {
"Type": "external"
},
"Endpoint": {
"Name": "StartUpDiagnosticsWriter",
"SendOnly": false,
"NServiceBusVersion": "10.2.0"
},
"Features": [
{
"Name": "NServiceBus.ReceiveStatisticsFeature",
"Enabled": false,
"Active": true,
"PrerequisiteStatus": {
"IsSatisfied": true,
"Reasons": []
},
"Dependencies": [],
"Version": "10.2.0",
...
Writing diagnostics to the log
Starting in version 10.2, diagnostics can also be written to the application log. This is useful in environments where writing to the file system is unavailable or impractical, such as containerized or serverless deployments.
endpointConfiguration.WriteDiagnosticsToLog();
When WriteDiagnosticsToLog is enabled, diagnostics are written to the log in addition to the default file-based output or any custom diagnostics writer. The AssemblyScanning section is automatically compacted to prevent exceeding log size limits, such as the Application Insights 64 KB telemetry limit. If the compacted diagnostics still exceed a safe threshold, the output is truncated and a warning is logged.
Writing to other targets
To take full control of how diagnostics are written:
endpointConfiguration.CustomDiagnosticsWriter(
(diagnostics, ct) =>
{
//custom logic to write data
return Task.CompletedTask;
});
Adding startup diagnostics sections
To extend the startup diagnostics with custom sections:
settings.AddStartupDiagnosticsSection(
sectionName: "MySection",
section: new
{
SomeSetting = "some data",
SomeOtherSetting = 10
});
Settings can be accessed from a feature or via the endpoint configuration.