System.IO.IOException: No space left on device : '/actions-runner/_diag/Worker_20260328-100041-utc.log' at System.IO.RandomAccess.WriteAtOffset(SafeFileHandle handle, ReadOnlySpan`1 buffer, Int64 fileOffset) at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder) at System.Diagnostics.TextWriterTraceListener.Flush() at GitHub.Runner.Common.HostTraceListener.WriteHeader(String source, TraceEventType eventType, Int32 id) at System.Diagnostics.TraceSource.TraceEvent(TraceEventType eventType, Int32 id, String message) at GitHub.Runner.Worker.Worker.RunAsync(String pipeIn, String pipeOut) at GitHub.Runner.Worker.Program.MainAsync(IHostContext context, String[] args) System.IO.IOException: No space left on device : '/actions-runner/_diag/Worker_20260328-100041-utc.log' at System.IO.RandomAccess.WriteAtOffset(SafeFileHandle handle, ReadOnlySpan`1 buffer, Int64 fileOffset) at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder) at System.Diagnostics.TextWriterTraceListener.Flush() at GitHub.Runner.Common.HostTraceListener.WriteHeader(String source, TraceEventType eventType, Int32 id) at System.Diagnostics.TraceSource.TraceEvent(TraceEventType eventType, Int32 id, String message) at GitHub.Runner.Common.Tracing.Error(Exception exception) at GitHub.Runner.Worker.Program.MainAsync(IHostContext context, String[] args) Unhandled exception. System.IO.IOException: No space left on device : '/actions-runner/_diag/Worker_20260328-100041-utc.log' at System.IO.RandomAccess.WriteAtOffset(SafeFileHandle handle, ReadOnlySpan`1 buffer, Int64 fileOffset) at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder) at System.Diagnostics.TextWriterTraceListener.Flush() at System.Diagnostics.TraceSource.Flush() at GitHub.Runner.Common.Tracing.Dispose(Boolean disposing) at GitHub.Runner.Common.Tracing.Dispose() at GitHub.Runner.Common.TraceManager.Dispose(Boolean disposing) at GitHub.Runner.Common.TraceManager.Dispose() at GitHub.Runner.Common.HostContext.Dispose(Boolean disposing) at GitHub.Runner.Common.HostContext.Dispose() at GitHub.Runner.Worker.Program.Main(String[] args)

System.IO.IOException: No space left on device : '/actions-runner/_diag/Worker_20260328-100041-utc.log' at System.IO.RandomAccess.WriteAtOffset(SafeFileHandle handle, ReadOnlySpan`1 buffer, Int64 fileOffset) at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder) at System.Diagnostics.TextWriterTraceListener.Flush() at GitHub.Runner.Common.HostTraceListener.WriteHeader(String source, TraceEventType eventType, Int32 id) at System.Diagnostics.TraceSource.TraceEvent(TraceEventType eventType, Int32 id, String message) at GitHub.Runner.Worker.Worker.RunAsync(String pipeIn, String pipeOut) at GitHub.Runner.Worker.Program.MainAsync(IHostContext context, String[] args) System.IO.IOException: No space left on device : '/actions-runner/_diag/Worker_20260328-100041-utc.log' at System.IO.RandomAccess.WriteAtOffset(SafeFileHandle handle, ReadOnlySpan`1 buffer, Int64 fileOffset) at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder) at System.Diagnostics.TextWriterTraceListener.Flush() at GitHub.Runner.Common.HostTraceListener.WriteHeader(String source, TraceEventType eventType, Int32 id) at System.Diagnostics.TraceSource.TraceEvent(TraceEventType eventType, Int32 id, String message) at GitHub.Runner.Common.Tracing.Error(Exception exception) at GitHub.Runner.Worker.Program.MainAsync(IHostContext context, String[] args) Unhandled exception. System.IO.IOException: No space left on device : '/actions-runner/_diag/Worker_20260328-100041-utc.log' at System.IO.RandomAccess.WriteAtOffset(SafeFileHandle handle, ReadOnlySpan`1 buffer, Int64 fileOffset) at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder) at System.Diagnostics.TextWriterTraceListener.Flush() at System.Diagnostics.TraceSource.Flush() at GitHub.Runner.Common.Tracing.Dispose(Boolean disposing) at GitHub.Runner.Common.Tracing.Dispose() at GitHub.Runner.Common.TraceManager.Dispose(Boolean disposing) at GitHub.Runner.Common.TraceManager.Dispose() at GitHub.Runner.Common.HostContext.Dispose(Boolean disposing) at GitHub.Runner.Common.HostContext.Dispose() at GitHub.Runner.Worker.Program.Main(String[] args)

The self-hosted runner lost communication with the server. Verify the machine is running and has a healthy network connection. Anything in your workflow that terminates the runner process, starves it for CPU/Memory, or blocks its network access can cause this error.

The run was canceled by @lucacillario.