Fix cudaErrorStreamCaptureUnsupported: Graph Capture Not Supported

Overview

cudaErrorStreamCaptureUnsupported occurs when attempting graph capture with operations that don't support it.

Error Messages

CUDA error: stream capture unsupported
cudaErrorStreamCaptureUnsupported

Common Causes

• •Synchronous operations during capture
• •Unsupported API calls in capture mode
• •Host-device sync in graph

Solutions

cudaStreamBeginCapture(stream, cudaStreamCaptureModeGlobal);
// Only async operations!
cudaMemcpyAsync(...);
kernel<<<...>>>;
// NOT cudaDeviceSynchronize();
cudaStreamEndCapture(stream, &graph);

// Supported: cudaMemcpyAsync, kernel launches, cudaEventRecord
// NOT supported: cudaDeviceSynchronize, cudaMemcpy (blocking)

Prevention Tips

• ✓Use only async APIs during capture
• ✓Test graph capture path separately

Code Examples

Before (Problematic)

Sync calls break capture.

cudaStreamBeginCapture(stream);
cudaDeviceSynchronize();  // Not supported!

After (Fixed)

Async only.

cudaStreamBeginCapture(stream);
cudaMemcpyAsync(...);
kernel<<<...>>>;
cudaStreamEndCapture(stream, &graph);

Frequently Asked Questions

Related Errors

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