diff --git a/Common/DCAFitter/include/DCAFitter/DCAFitterN.h b/Common/DCAFitter/include/DCAFitter/DCAFitterN.h
index 2e36f7588e8be..8ded804751de1 100644
--- a/Common/DCAFitter/include/DCAFitter/DCAFitterN.h
+++ b/Common/DCAFitter/include/DCAFitter/DCAFitterN.h
@@ -41,19 +41,20 @@ struct TrackCovI {
     // (otherwise for quazi-collinear tracks the X will not be constrained)
     float cyy = trc.getSigmaY2(), czz = trc.getSigmaZ2(), cyz = trc.getSigmaZY(), cxx = cyy * xerrFactor;
     float detYZ = cyy * czz - cyz * cyz;
-    if (detYZ > 0.) {
-      auto detYZI = 1. / detYZ;
-      sxx = 1. / cxx;
-      syy = czz * detYZI;
-      syz = -cyz * detYZI;
-      szz = cyy * detYZI;
-    } else {
+    if (detYZ <= 0.) {
 #ifndef GPUCA_GPUCODE
-      throw std::runtime_error("invalid track covariance");
+      printf("overriding invalid track covariance from %s\n", trc.asString().c_str());
 #else
-      printf("invalid track covariance\n");
+      printf("overriding invalid track covariance cyy:%e czz:%e cyz:%e\n", cyy, czz, cyz);
 #endif
+      cyz = o2::gpu::GPUCommonMath::Sqrt(cyy * czz) * (cyz > 0 ? 0.98f : -0.98f);
+      detYZ = cyy * czz - cyz * cyz;
     }
+    auto detYZI = 1. / detYZ;
+    sxx = 1. / cxx;
+    syy = czz * detYZI;
+    syz = -cyz * detYZI;
+    szz = cyy * detYZI;
   }
 };
 
diff --git a/Detectors/GLOQC/src/MatchITSTPCQC.cxx b/Detectors/GLOQC/src/MatchITSTPCQC.cxx
index f0345175b9a59..6e14f9eb16c8b 100644
--- a/Detectors/GLOQC/src/MatchITSTPCQC.cxx
+++ b/Detectors/GLOQC/src/MatchITSTPCQC.cxx
@@ -477,6 +477,21 @@ void MatchITSTPCQC::run(o2::framework::ProcessingContext& ctx)
   if (mTimestamp == -1 && mDoK0QC) {
     // we have not yet initialized the SVertexer params; let's do it
     ctx.inputs().get<o2::vertexing::SVertexerParams*>("SVParam");
+    const auto& svparam = o2::vertexing::SVertexerParams::Instance();
+    mFitterV0.setUseAbsDCA(svparam.useAbsDCA);
+    mFitterV0.setMaxR(svparam.maxRIni);
+    mFitterV0.setMinParamChange(svparam.minParamChange);
+    mFitterV0.setMinRelChi2Change(svparam.minRelChi2Change);
+    mFitterV0.setMaxDZIni(svparam.maxDZIni);
+    mFitterV0.setMaxDXYIni(svparam.maxDXYIni);
+    mFitterV0.setMaxChi2(svparam.maxChi2);
+    mFitterV0.setMatCorrType(o2::base::Propagator::MatCorrType(svparam.matCorr));
+    mFitterV0.setUsePropagator(svparam.usePropagator);
+    mFitterV0.setRefitWithMatCorr(svparam.refitWithMatCorr);
+    mFitterV0.setMaxStep(svparam.maxStep);
+    mFitterV0.setMaxSnp(svparam.maxSnp);
+    mFitterV0.setMinXSeed(svparam.minXSeed);
+
     mTimestamp = ctx.services().get<o2::framework::TimingInfo>().creation;
     auto grplhcif = o2::base::GRPGeomHelper::instance().getGRPLHCIF();
     if (grplhcif->getBeamZ(0) != 1 || grplhcif->getBeamZ(1) != 1) {
@@ -962,6 +977,7 @@ void MatchITSTPCQC::run(o2::framework::ProcessingContext& ctx)
 
   if (mDoK0QC && mRecoCont.getPrimaryVertices().size() > 0) {
     // now doing K0S
+    mFitterV0.setBz(mBz);
     const auto pvertices = mRecoCont.getPrimaryVertices();
     LOG(info) << "****** Number of PVs                 = " << pvertices.size();