diff --git a/src/include/ranges/crange.h b/src/include/ranges/crange.h
index 4083c68..5a9366e 100644
--- a/src/include/ranges/crange.h
+++ b/src/include/ranges/crange.h
@@ -185,7 +185,8 @@ namespace CNORXZ
 	 */
 	SizeT get(SizeT pos) const;
 
-	/** return position for given meta data
+	/** return position for given meta data.
+	    Returns size() if metaPos is out of scope.
 	    @param metaPos meta data, size type
 	 */
 	SizeT getMeta(SizeT metaPos) const;
diff --git a/src/include/ranges/urange.cc.h b/src/include/ranges/urange.cc.h
index 41efa29..b8878f2 100644
--- a/src/include/ranges/urange.cc.h
+++ b/src/include/ranges/urange.cc.h
@@ -299,8 +299,12 @@ namespace CNORXZ
 	auto b = mSpace.begin();
 	auto e = mSpace.end();
 	auto i = std::lower_bound(b, e, meta, std::less<MetaT>());
-	CXZ_ASSERT(i != e, "element with meta data = " << toString(meta) << " not in range"); // check this first, otherwise the next test may potentially result in a seg fault!
-	CXZ_ASSERT(*i == meta, "element with meta data = " << toString(meta) << " not in range");
+	if(i == e){
+	    return size();
+	}
+	if(*i != meta){
+	    return size();
+	}
 	return i - b;
     }
 
diff --git a/src/include/ranges/urange.h b/src/include/ranges/urange.h
index adcbf25..7c3605a 100644
--- a/src/include/ranges/urange.h
+++ b/src/include/ranges/urange.h
@@ -197,6 +197,7 @@ namespace CNORXZ
 	const MetaType* get() const;
 
 	/** Get range position for given meta data.
+	    Returns size() if metaPos is not part of the range.
 	    @param metaPos Meta data.
 	    @return Position of the given meta data if it is contained by the range.
 	 */
diff --git a/src/lib/ranges/crange.cc b/src/lib/ranges/crange.cc
index 9b797d3..c5123b6 100644
--- a/src/lib/ranges/crange.cc
+++ b/src/lib/ranges/crange.cc
@@ -115,7 +115,7 @@ namespace CNORXZ
     
     CIndex& CIndex::at(const SizeT& metaPos)
     {
-	IB::mPos = metaPos;
+	IB::mPos = metaPos < lmax().val() ? metaPos : lmax().val();
 	return *this;
     }
 
@@ -204,6 +204,9 @@ namespace CNORXZ
     
     SizeT CRange::getMeta(SizeT metaPos) const
     {
+	if(metaPos >= size()){
+	    return size();
+	}
 	return metaPos;
     }
     
diff --git a/src/opt/hdf5/lib/h5_group.cc b/src/opt/hdf5/lib/h5_group.cc
index 37f8bc3..e7f4d32 100644
--- a/src/opt/hdf5/lib/h5_group.cc
+++ b/src/opt/hdf5/lib/h5_group.cc
@@ -93,6 +93,7 @@ namespace CNORXZ
 		const String next = name.substr(delimpos+1);
 		auto g = getGroup(thisname);
 		g->open();
+		CHECK;
 		return g->get(next);
 	    }
 	    auto i = this->getIndexTo(thisname);
@@ -101,7 +102,7 @@ namespace CNORXZ
 
 	Sptr<Group> Group::getGroup(const String& name) const
 	{
-	    auto group = this->get(name);
+	    ContentPtr group = this->get(name);
 	    CXZ_ASSERT(group->type() == ContentType::GROUP,
 		       "element '" << name << "' is not of type GROUP");
 	    return std::dynamic_pointer_cast<Group>( group );
@@ -236,6 +237,7 @@ namespace CNORXZ
 	    auto dvec = [](const String& n) { return Vector<DType>({DType(n)}); };
 	    auto i = mCont.begin();
 	    i.at(dvec(name));
+	    CXZ_ASSERT(i != mCont.end(), "no element '" << name << "' in group " << path());
 	    return i;
 	}
 
@@ -245,6 +247,7 @@ namespace CNORXZ
 	    auto dvec = [](const String& n) { return Vector<DType>({DType(n)}); };
 	    auto i = mCont.begin();
 	    i.at(dvec(name));
+	    CXZ_ASSERT(i != mCont.end(), "no element '" << name << "' in group " << path());
 	    return i;
 	}
 	
diff --git a/src/opt/mpi/include/rrange.cc.h b/src/opt/mpi/include/rrange.cc.h
index 18e9bfe..8efabf5 100644
--- a/src/opt/mpi/include/rrange.cc.h
+++ b/src/opt/mpi/include/rrange.cc.h
@@ -274,8 +274,7 @@ namespace CNORXZ
 	template <class IndexI, class IndexK>
 	decltype(auto) RIndex<IndexI,IndexK>::xpr(const Sptr<RIndex<IndexI,IndexK>>& _this) const
 	{
-	    CXZ_ERROR("not implemented");
-	    return 0;
+	    return _this->local()->xpr( _this->local() );
 	}
 
 	template <class IndexI, class IndexK>