diff --git a/RecoTracker/PixelVertexFinding/plugins/alpaka/fitVertices.h b/RecoTracker/PixelVertexFinding/plugins/alpaka/fitVertices.h
index a8c428e2f5a00..2f78723e61d9c 100644
--- a/RecoTracker/PixelVertexFinding/plugins/alpaka/fitVertices.h
+++ b/RecoTracker/PixelVertexFinding/plugins/alpaka/fitVertices.h
@@ -74,7 +74,19 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::vertexFinder {
     alpaka::syncBlockThreads(acc);
     // reuse nn
     for (auto i : cms::alpakatools::uniform_elements(acc, foundClusters)) {
-      ALPAKA_ASSERT_ACC(wv[i] > 0.f);
+      bool const wv_cond = (wv[i] > 0.f);
+      if (not wv_cond) {
+        printf("ERROR: wv[%d] (%f) > 0.f failed\n", i, wv[i]);
+        // printing info on tracks associated to this vertex
+        for (auto trk_i = 0u; trk_i < nt; ++trk_i) {
+          if (iv[trk_i] != int(i)) {
+            continue;
+          }
+          printf("   iv[%d]=%d zt[%d]=%f ezt2[%d]=%f\n", trk_i, iv[trk_i], trk_i, zt[trk_i], trk_i, ezt2[trk_i]);
+        }
+        ALPAKA_ASSERT_ACC(false);
+      }
+
       zv[i] /= wv[i];
       nn[i] = -1;  // ndof
     }