diff --git a/opm/simulators/wells/BlackoilWellModelGeneric.cpp b/opm/simulators/wells/BlackoilWellModelGeneric.cpp
index 66d277629..fdfb59857 100644
--- a/opm/simulators/wells/BlackoilWellModelGeneric.cpp
+++ b/opm/simulators/wells/BlackoilWellModelGeneric.cpp
@@ -912,6 +912,7 @@ BlackoilWellModelGeneric::
 assignNodeValues(std::map<std::string, data::NodeData>& nodevalues, const int reportStepIdx) const
 {
     nodevalues.clear();
+    if (reportStepIdx < 0) return;
 
     for (const auto& [node, pressure] : node_pressures_) {
         nodevalues.emplace(node, data::NodeData{pressure});
@@ -938,7 +939,9 @@ assignNodeValues(std::map<std::string, data::NodeData>& nodevalues, const int re
         assert(it != nodevalues.end() );
         it->second.converged_pressure = converged_pressure;
         // Assign node values of group to GPR:WELLNAME
-        const auto& group = schedule().getGroup(node, reportStepIdx);
+        const auto& sched = schedule();
+        if (!sched.hasGroup(node, reportStepIdx)) continue;
+        const auto& group = sched.getGroup(node, reportStepIdx);
         for (const std::string& wellname : group.wells()) {
                 auto it2 = nodevalues.find(wellname);
                 assert(it2 != nodevalues.end());