diff --git a/CI/test_coverage.py b/CI/test_coverage.py
index 06b13a06abb..0488a71d85d 100755
--- a/CI/test_coverage.py
+++ b/CI/test_coverage.py
@@ -41,7 +41,7 @@ def call(cmd):
 
 ret, gcovr_version_text = check_output(["gcovr", "--version"])
 gcovr_version = tuple(
-    map(int, re.match("gcovr (\d+\.\d+)", gcovr_version_text).group(1).split("."))
+    map(int, re.match(r"gcovr (\d+\.\d+)", gcovr_version_text).group(1).split("."))
 )
 
 extra_flags = []
@@ -63,7 +63,7 @@ def call(cmd):
 if not os.path.exists(coverage_dir):
     os.makedirs(coverage_dir)
 
-excludes = ["-e", "../Tests/", "-e", ".*json\.hpp"]
+excludes = ["-e", "../Tests/", "-e", r".*json\.hpp"]
 
 # create the html report
 call(
diff --git a/Core/include/Acts/Geometry/TrackingVolume.hpp b/Core/include/Acts/Geometry/TrackingVolume.hpp
index 290e5c21425..b208eefa54b 100644
--- a/Core/include/Acts/Geometry/TrackingVolume.hpp
+++ b/Core/include/Acts/Geometry/TrackingVolume.hpp
@@ -322,6 +322,25 @@ class TrackingVolume : public Volume {
   /// @param portal The portal to add
   void addPortal(std::shared_ptr<Portal> portal);
 
+  using MutableSurfaceRange =
+      detail::TransformRange<detail::Dereference,
+                             std::vector<std::shared_ptr<Surface>>>;
+  using SurfaceRange =
+      detail::TransformRange<detail::ConstDereference,
+                             const std::vector<std::shared_ptr<Surface>>>;
+
+  /// Return all surfaces registered under this tracking volume
+  /// @return the range of surfaces
+  SurfaceRange surfaces() const;
+
+  /// Return mutable view of the registered surfaces under this tracking volume
+  /// @return the range of surfaces
+  MutableSurfaceRange surfaces();
+
+  /// Add a surface to this tracking volume
+  /// @param surface The surface to add
+  void addSurface(std::shared_ptr<Surface> surface);
+
   /// Add a child volume to this tracking volume
   /// @param volume The volume to add
   /// @note The @p volume will have its mother volume assigned to @p this.
@@ -516,6 +535,7 @@ class TrackingVolume : public Volume {
 
   std::vector<std::unique_ptr<TrackingVolume>> m_volumes;
   std::vector<std::shared_ptr<Portal>> m_portals;
+  std::vector<std::shared_ptr<Surface>> m_surfaces;
 };
 
 }  // namespace Acts
diff --git a/Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp b/Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp
index 2de65a78a07..92a6a4f76ba 100644
--- a/Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp
+++ b/Core/include/Acts/TrackFitting/GlobalChiSquareFitter.hpp
@@ -610,10 +610,10 @@ class Gx2Fitter {
 
       // Check if we can stop to propagate
       if (result.measurementStates == inputMeasurements->size()) {
-        ACTS_INFO("Actor: finish: All measurements have been found.");
+        ACTS_DEBUG("Actor: finish: All measurements have been found.");
         result.finished = true;
       } else if (state.navigation.navigationBreak) {
-        ACTS_INFO("Actor: finish: navigationBreak.");
+        ACTS_DEBUG("Actor: finish: navigationBreak.");
         result.finished = true;
       }
 
@@ -1218,7 +1218,7 @@ class Gx2Fitter {
 
         // We only consider states with a measurement (and/or material)
         if (!stateHasMeasurement && !doMaterial) {
-          ACTS_INFO("    Skip state.");
+          ACTS_DEBUG("    Skip state.");
           continue;
         }
 
@@ -1388,6 +1388,9 @@ class Gx2Fitter {
 
     // Propagate again with the final covariance matrix. This is necessary to
     // obtain the propagated covariance for each state.
+    // We also need to recheck the result and find the tipIndex, because at this
+    // step, we will not ignore the boundary checks for measurement surfaces. We
+    // want to create trackstates only on surfaces, that we actually hit.
     if (gx2fOptions.nUpdateMax > 0) {
       ACTS_VERBOSE("final deltaParams:\n" << deltaParams);
       ACTS_VERBOSE("Propagate with the final covariance.");
@@ -1413,7 +1416,33 @@ class Gx2Fitter {
       auto& r = propagatorState.template get<Gx2FitterResult<traj_t>>();
       r.fittedStates = &trackContainer.trackStateContainer();
 
-      m_propagator.template propagate(propagatorState);
+      auto propagationResult = m_propagator.template propagate(propagatorState);
+
+      // Run the fitter
+      auto result = m_propagator.template makeResult(std::move(propagatorState),
+                                                     propagationResult,
+                                                     propagatorOptions, false);
+
+      if (!result.ok()) {
+        ACTS_ERROR("Propagation failed: " << result.error());
+        return result.error();
+      }
+
+      auto& propRes = *result;
+      GX2FResult gx2fResult = std::move(propRes.template get<GX2FResult>());
+
+      if (!gx2fResult.result.ok()) {
+        ACTS_INFO("GlobalChiSquareFitter failed in actor: "
+                  << gx2fResult.result.error() << ", "
+                  << gx2fResult.result.error().message());
+        return gx2fResult.result.error();
+      }
+
+      if (tipIndex != gx2fResult.lastMeasurementIndex) {
+        ACTS_INFO("Final fit used unreachable measurements.");
+        return Experimental::GlobalChiSquareFitterError::
+            UsedUnreachableMeasurements;
+      }
     }
 
     if (!trackContainer.hasColumn(
diff --git a/Core/include/Acts/TrackFitting/GlobalChiSquareFitterError.hpp b/Core/include/Acts/TrackFitting/GlobalChiSquareFitterError.hpp
index 7c95750a3f6..5bc4c55b3e2 100644
--- a/Core/include/Acts/TrackFitting/GlobalChiSquareFitterError.hpp
+++ b/Core/include/Acts/TrackFitting/GlobalChiSquareFitterError.hpp
@@ -19,6 +19,7 @@ enum class GlobalChiSquareFitterError {
   DidNotConverge = 2,
   NotEnoughMeasurements = 3,
   UpdatePushedToNewVolume = 4,
+  UsedUnreachableMeasurements = 5,
 };
 
 std::error_code make_error_code(
diff --git a/Core/src/Geometry/TrackingVolume.cpp b/Core/src/Geometry/TrackingVolume.cpp
index d2c1124a1ae..79ffdc9d180 100644
--- a/Core/src/Geometry/TrackingVolume.cpp
+++ b/Core/src/Geometry/TrackingVolume.cpp
@@ -663,7 +663,25 @@ TrackingVolume::MutablePortalRange TrackingVolume::portals() {
 }
 
 void TrackingVolume::addPortal(std::shared_ptr<Portal> portal) {
+  if (portal == nullptr) {
+    throw std::invalid_argument("Portal is nullptr");
+  }
   m_portals.push_back(std::move(portal));
 }
 
+TrackingVolume::SurfaceRange TrackingVolume::surfaces() const {
+  return SurfaceRange{m_surfaces};
+}
+
+TrackingVolume::MutableSurfaceRange TrackingVolume::surfaces() {
+  return MutableSurfaceRange{m_surfaces};
+}
+
+void TrackingVolume::addSurface(std::shared_ptr<Surface> surface) {
+  if (surface == nullptr) {
+    throw std::invalid_argument("Surface is nullptr");
+  }
+  m_surfaces.push_back(std::move(surface));
+}
+
 }  // namespace Acts
diff --git a/Core/src/TrackFitting/GlobalChiSquareFitterError.cpp b/Core/src/TrackFitting/GlobalChiSquareFitterError.cpp
index 98beceb8cb1..3a3cc713173 100644
--- a/Core/src/TrackFitting/GlobalChiSquareFitterError.cpp
+++ b/Core/src/TrackFitting/GlobalChiSquareFitterError.cpp
@@ -32,6 +32,8 @@ class GlobalChiSquareFitterErrorCategory : public std::error_category {
         return "Gx2f: Not enough measurements.";
       case GlobalChiSquareFitterError::UpdatePushedToNewVolume:
         return "Gx2f: Update pushed the parameters to a new volume.";
+      case GlobalChiSquareFitterError::UsedUnreachableMeasurements:
+        return "Gx2f: Final fit used unreachable measurements.";
       default:
         return "unknown";
     }