diff --git a/src/app/formulaire/ngparam.ts b/src/app/formulaire/ngparam.ts
index 10ed519628c99864921882ea8ba5d925b68f5fc1..9d9ce7c9c873d8e1238c6d41da65a0494e859d09 100644
--- a/src/app/formulaire/ngparam.ts
+++ b/src/app/formulaire/ngparam.ts
@@ -98,6 +98,7 @@ export class NgParameter extends InputField implements Observer {
                         // calculated param ?
                         if (targetParam.valueMode === ParamValueMode.CALCUL) {
                             // was the result already computed ?
+                            // @WAARNING .result might be set but the computation might have failed (dichotomy for ex.)
                             if (p.referencedValue.nub.result) {
                                 if (p.referencedValue.hasMultipleValues()) {
                                     // like LIST mode
@@ -110,7 +111,8 @@ export class NgParameter extends InputField implements Observer {
                                     if (vCalc) {
                                         valuePreview = String(vCalc.toFixed(nDigits));
                                     } else {
-                                        throw new Error("NgParameter.preview() : No vCalc for computed target Nub !");
+                                        // computation has been run but has failed
+                                        valuePreview = i18n.localizeText("INFO_PARAMFIELD_CALCULATION_FAILED");
                                     }
                                 }
                             } else {
diff --git a/src/locale/messages.en.json b/src/locale/messages.en.json
index beb07be9fd2ebccfc24adc2fcda97df98a05f50b..d4e1a6420e5f11e1e8e4fbb05ad50f020cf47dac 100644
--- a/src/locale/messages.en.json
+++ b/src/locale/messages.en.json
@@ -159,6 +159,7 @@
     "INFO_PARAMFIELD_GRAPH_TYPE_HISTOGRAM": "Histogram",
     "INFO_PARAMFIELD_GRAPH_SELECT_X_AXIS": "Variable for X axis",
     "INFO_PARAMFIELD_GRAPH_SELECT_Y_AXIS": "Variable for Y axis",
+    "INFO_PARAMFIELD_CALCULATION_FAILED": "Calculation failed",
     "INFO_PARAMFIELD_IN_CALCULATION": "In calculation",
     "INFO_PARAMFIELD_IN_CALCULATION_INITIAL_VALUE": "initial value",
     "INFO_PARAMFIELD_PARAMCALCULER": "Calculate",
diff --git a/src/locale/messages.fr.json b/src/locale/messages.fr.json
index 2dddd1782c9445c20efb72e7314f663a016d02a4..8627ade07888a7da9d144dd827c5e0b05bd168f0 100644
--- a/src/locale/messages.fr.json
+++ b/src/locale/messages.fr.json
@@ -159,6 +159,7 @@
     "INFO_PARAMFIELD_GRAPH_TYPE_HISTOGRAM": "Histogramme",
     "INFO_PARAMFIELD_GRAPH_SELECT_X_AXIS": "Variable en abscisse",
     "INFO_PARAMFIELD_GRAPH_SELECT_Y_AXIS": "Variable en ordonnée",
+    "INFO_PARAMFIELD_CALCULATION_FAILED": "Échec du calcul",
     "INFO_PARAMFIELD_IN_CALCULATION": "En calcul",
     "INFO_PARAMFIELD_IN_CALCULATION_INITIAL_VALUE": "valeur initiale",
     "INFO_PARAMFIELD_PARAMCALCULER": "calculer",