Fix cudaErrorSynchronizationError: Sync Operation Failed

Overview

cudaErrorSynchronizationError indicates a failure during synchronization, often revealing earlier kernel errors.

Error Messages

CUDA error: synchronization error
cudaErrorSynchronizationError

Common Causes

• •Kernel error detected at sync
• •Stream corruption
• •Device lost during operation

Solutions

kernelA<<<...>>>();
cudaError_t err = cudaGetLastError();  // Check launch
cudaDeviceSynchronize();  // Checks execution
err = cudaGetLastError();  // Get async errors

Prevention Tips

• ✓Check errors after every kernel
• ✓Use compute-sanitizer to find root cause

Code Examples

Before (Problematic)

Root cause is kernel, not sync.

kernel<<<...>>>();
cudaDeviceSynchronize();  // Error appears here

After (Fixed)

Check both launch and execution.

kernel<<<...>>>();
CHECK_CUDA(cudaGetLastError());
CHECK_CUDA(cudaDeviceSynchronize());

Frequently Asked Questions

Related Errors

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