diff --git a/src/leastsquares.cpp b/src/leastsquares.cpp
index 9566d1ac..0e35bbdd 100644
--- a/src/leastsquares.cpp
+++ b/src/leastsquares.cpp
@@ -757,7 +757,7 @@ bool LeastSquares::iterate(bool invert, COMPUTE_TYPE compute_type)
             m_interrupted = true;
         //std::cout<<error_msg.str()<<std::flush;
         //project->outputConversion();
-        project->updateEllipsoids();
+        m_calculusError = m_calculusError || !project->updateEllipsoids();
         return !m_calculusError;
     }
 
@@ -936,7 +936,10 @@ bool LeastSquares::iterate(bool invert, COMPUTE_TYPE compute_type)
     if (!m_calculusError)
     {
         project->outputConversion();
-        if (invert) project->updateEllipsoids();
+        if (invert)
+        {
+            m_calculusError = m_calculusError || !project->updateEllipsoids();
+        }
     }
     return !m_calculusError;
 }
diff --git a/src/leastsquares.h b/src/leastsquares.h
index 4b945ea2..b89a3aaa 100644
--- a/src/leastsquares.h
+++ b/src/leastsquares.h
@@ -120,6 +120,7 @@ class LeastSquares
     bool m_interrupted;//<if computatio interrupted by max iter, no redondancy or user interruption (button)
     bool m_internalConstr;//m_internalConstr is update during initialize(), and used in iterate
     int rankDeficiency;//< if AtPA rank is not equal to cols
+    bool computeKernel();//returns true if dim(kern)>0
 
 protected:
     bool prepareSolve(spSolver &solver);
@@ -134,7 +135,6 @@ class LeastSquares
     bool testStability(spSolver &solver);
 #endif
 
-    bool computeKernel();//returns true if dim(kern)>0
     void kernelMessage();
     MatrixOrdering matrixOrdering;
     std::vector <std::unique_ptr<Obs> > ICobs;//internal constraints obs
diff --git a/src/point.cpp b/src/point.cpp
index 97242936..70f91b00 100644
--- a/src/point.cpp
+++ b/src/point.cpp
@@ -80,7 +80,7 @@ std::string Point::toString() const
     if (ellipsoid.isSet())
     {
         oss<<"   var:";
-        for (int i=0;i<dimension;i++)
+        for (int i=0;i<3;i++)
             oss<<" "<<ellipsoid.get_variance(i);
     }
     return oss.str();
@@ -468,7 +468,7 @@ bool Point::initCoordinates()
     return true;
 }
 
-void Point::set_posteriori_variance(const MatX &Qxx)
+bool Point::set_posteriori_variance(const MatX &Qxx)
 {
     for (int i=0;i<3;i++)
     {
@@ -484,6 +484,14 @@ void Point::set_posteriori_variance(const MatX &Qxx)
     //std::cout<<"For point "<<name<<":\n";
 
     ellipsoid.compute_eigenvalues(Project::theone()->lsquares.sigma_0);
+    for (int i=0;i<3;i++)
+    {
+        if (!std::isfinite(ellipsoid.get_ellipsAxe(i)))
+            return false;
+        if (!std::isfinite(ellipsoid.get_variance(i)))
+            return false;
+    }
+    return true;
 }
 
 void Point::create_coordinates_constraits()
diff --git a/src/point.h b/src/point.h
index a1475ca9..0bc22198 100644
--- a/src/point.h
+++ b/src/point.h
@@ -116,7 +116,7 @@ class Point
                             STATION_CREATION_MODE creation_mode=STATION_CREATION_MODE::ST_CREAT_ALLOWED);//where to add new observations
 
     bool initCoordinates();
-    void set_posteriori_variance(const MatX &Qxx);
+    bool set_posteriori_variance(const MatX &Qxx); //< return false if error
     std::string toString() const;
 
     std::vector<Point *> pointsMeasured() const;//<list of measured point from this
diff --git a/src/project.cpp b/src/project.cpp
index c1fbe7d4..504cb660 100644
--- a/src/project.cpp
+++ b/src/project.cpp
@@ -1444,13 +1444,23 @@ void Project::outputConversion()
     }
 }
 
-void Project::updateEllipsoids()
+bool Project::updateEllipsoids()
 {
     biggestEllips = 0;
-    if (!invertedMatrix) return;
+    if (!invertedMatrix) return true;
 
     for (auto & point : points)
-        point.set_posteriori_variance(lsquares.Qxx);
+    {
+        bool ptok = point.set_posteriori_variance(lsquares.Qxx);
+        if (!ptok && std::isfinite(lsquares.sigma_0))
+        {
+            Project::theInfo()->warning(INFO_LS,1,
+                                        QT_TRANSLATE_NOOP("QObject","Error on output sigmas of point %s: %s"),
+                                        point.name.c_str(), point.ellipsoid.sigmasToString(lsquares.sigma_0).c_str());
+            lsquares.computeKernel();
+            return false;
+        }
+    }
 
     int nbrEllipsTooBig = 0;
     Point *ptbig = nullptr;
@@ -1478,7 +1488,9 @@ void Project::updateEllipsoids()
         Project::theInfo()->warning(INFO_LS,1,
                                     QT_TRANSLATE_NOOP("QObject","and sigma0 = %.3f"),
                                     lsquares.sigma_0);
+        lsquares.computeKernel();
     }
+    return true;
 }
 
 bool Project::computation(bool invert, bool saveNew)
diff --git a/src/project.h b/src/project.h
index 7ade5f02..cb2fa0ec 100644
--- a/src/project.h
+++ b/src/project.h
@@ -66,7 +66,7 @@ class Project
     bool exportSightMatrix(const std::string &filename);
 
     bool computation(bool invert, bool saveNew);
-    void updateEllipsoids();
+    bool updateEllipsoids(); //< return false if error
 
     bool saveasJSON();