diff --git a/src/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQDefine.cpp b/src/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQDefine.cpp
index 1b9f17e21..cfbb2fed0 100644
--- a/src/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQDefine.cpp
+++ b/src/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQDefine.cpp
@@ -19,13 +19,15 @@
 #include <iostream>
 #include <cstring>
 #include <tuple>
-
+#include <fmt/format.h>
+#include <exception>
 
 #include <opm/parser/eclipse/Parser/ParseContext.hpp>
 #include <opm/parser/eclipse/Parser/ErrorGuard.hpp>
 #include <opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQASTNode.hpp>
 #include <opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQDefine.hpp>
 #include <opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQEnums.hpp>
+#include <opm/common/OpmLog/OpmLog.hpp>
 
 #include "../../../Parser/raw/RawConsts.hpp"
 #include "UDQToken.hpp"
@@ -240,15 +242,26 @@ void UDQDefine::required_summary(std::unordered_set<std::string>& summary_keys)
 }
 
 UDQSet UDQDefine::eval(const UDQContext& context) const {
-    UDQSet res = this->ast->eval(this->m_var_type, context);
-    res.name( this->m_keyword );
-
-    if (!dynamic_type_check(this->var_type(), res.var_type())) {
-        std::string msg = "Invalid runtime type conversion detected when evaluating UDQ";
-        throw std::invalid_argument(msg);
+    std::optional<UDQSet> res;
+    try {
+        res = this->ast->eval(this->m_var_type, context);
+        res->name( this->m_keyword );
+        if (!dynamic_type_check(this->var_type(), res->var_type())) {
+            std::string msg = "Invalid runtime type conversion detected when evaluating UDQ";
+            throw std::invalid_argument(msg);
+        }
+    } catch (const std::exception& exc) {
+        auto msg = fmt::format("Problem evaluating UDQ {}\n"
+                               "In {} line {}\n"
+                               "Internal error: {}", this->m_keyword, this->m_location.filename, this->m_location.lineno, exc.what());
+        OpmLog::error(msg);
+        std::throw_with_nested(exc);
     }
+    if (!res)
+        throw std::logic_error("Bug in UDQDefine::eval()");
 
-    if (res.var_type() == UDQVarType::SCALAR) {
+
+    if (res->var_type() == UDQVarType::SCALAR) {
         /*
           If the right hand side evaluates to a scalar that scalar value should
           be set for all wells in the wellset:
@@ -265,7 +278,7 @@ UDQSet UDQDefine::eval(const UDQContext& context) const {
           regarding the semantics of group sets.
         */
 
-        const auto& scalar_value = res[0].value();
+        const auto& scalar_value = res->operator[](0).value();
         if (this->var_type() == UDQVarType::WELL_VAR) {
             const std::vector<std::string> wells = context.wells();
             UDQSet well_res = UDQSet::wells(this->m_keyword, wells);
@@ -287,7 +300,7 @@ UDQSet UDQDefine::eval(const UDQContext& context) const {
         }
     }
 
-    return res;
+    return *res;
 }
 
 const KeywordLocation& UDQDefine::location() const {
diff --git a/src/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQSet.cpp b/src/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQSet.cpp
index 5a2827293..9f03dba16 100644
--- a/src/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQSet.cpp
+++ b/src/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQSet.cpp
@@ -19,6 +19,7 @@
 #include <fnmatch.h>
 #include <algorithm>
 #include <cmath>
+#include <fmt/format.h>
 
 #include <opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQSet.hpp>
 
@@ -485,8 +486,10 @@ UDQSet udq_cast(const UDQSet& lhs, const UDQSet& rhs)
 {
     if (lhs.size() != rhs.size()) {
         if (lhs.var_type() != UDQVarType::SCALAR) {
-            printf("s1: %ld  s2: %ld \n", lhs.size(), rhs.size());
-            throw std::logic_error("Type/size mismatch");
+            auto msg = fmt::format("Type/size mismatch when combining UDQs {}(size={}, type={}) and {}(size={}, type={})",
+                                   lhs.name(), lhs.size(), lhs.var_type(),
+                                   rhs.name(), rhs.size(), rhs.var_type());
+            throw std::logic_error(msg);
         }
 
         if (rhs.var_type() == UDQVarType::WELL_VAR)
diff --git a/src/opm/parser/eclipse/EclipseState/SummaryConfig/SummaryConfig.cpp b/src/opm/parser/eclipse/EclipseState/SummaryConfig/SummaryConfig.cpp
index 5e62702c5..0186743e4 100644
--- a/src/opm/parser/eclipse/EclipseState/SummaryConfig/SummaryConfig.cpp
+++ b/src/opm/parser/eclipse/EclipseState/SummaryConfig/SummaryConfig.cpp
@@ -922,7 +922,7 @@ inline void keywordMISC( SummaryConfig::keyword_list& list,
         if (!udq.has_unit(location.keyword)) {
             std::string msg = "Summary output requested for UDQ {keyword}\n"
                               "In {file} line {line}\n"
-                              "No unit define in the SCHEDULE section";
+                              "No unit defined in the SCHEDULE section for {keyword}";
             parseContext.handleError(ParseContext::SUMMARY_UDQ_MISSING_UNIT, msg, location, errors);
         }
     }
diff --git a/tests/parser/UDQTests.cpp b/tests/parser/UDQTests.cpp
index 331d73a0e..f5e62a065 100644
--- a/tests/parser/UDQTests.cpp
+++ b/tests/parser/UDQTests.cpp
@@ -2189,7 +2189,7 @@ UDQ
     UDQState udq_state(undefined_value);
     SummaryState st(std::chrono::system_clock::now());
 
-    BOOST_CHECK_THROW(udq.eval(0, st, udq_state), std::out_of_range);
+    BOOST_CHECK_THROW(udq.eval(0, st, udq_state), std::exception);
 }