diff -urN boost_1_80_0/boost/unordered/detail/fca.hpp boost_1_80_1/boost/unordered/detail/fca.hpp
--- boost_1_80_0/boost/unordered/detail/fca.hpp	2022-08-03 22:47:16.000000000 -0400
+++ boost_1_80_1/boost/unordered/detail/fca.hpp	2022-08-24 19:44:43.139787681 -0400
@@ -646,7 +646,7 @@
 
         size_type bucket_count() const { return size_; }
 
-        iterator begin() const { return ++at(size_); }
+        iterator begin() const { return size_ == 0 ? end() : ++at(size_); }
 
         iterator end() const
         {
@@ -660,6 +660,10 @@
 
         local_iterator begin(size_type n) const
         {
+          if (size_ == 0) {
+            return this->end(n);
+          }
+
           return local_iterator(
             (buckets + static_cast<difference_type>(n))->next);
         }
@@ -670,12 +674,16 @@
 
         iterator at(size_type n) const
         {
-          std::size_t const N = group::N;
+          if (size_ > 0) {
+            std::size_t const N = group::N;
 
-          iterator pbg(buckets + static_cast<difference_type>(n),
-            groups + static_cast<difference_type>(n / N));
+            iterator pbg(buckets + static_cast<difference_type>(n),
+              groups + static_cast<difference_type>(n / N));
 
-          return pbg;
+            return pbg;
+          } else {
+            return this->end();
+          }
         }
 
         span<Bucket> raw()
diff -urN boost_1_80_0/boost/unordered/detail/implementation.hpp boost_1_80_1/boost/unordered/detail/implementation.hpp
--- boost_1_80_0/boost/unordered/detail/implementation.hpp	2022-08-03 22:47:16.000000000 -0400
+++ boost_1_80_1/boost/unordered/detail/implementation.hpp	2022-08-24 19:44:43.139787681 -0400
@@ -2054,12 +2054,14 @@
 
         std::size_t bucket_size(std::size_t index) const
         {
-          bucket_iterator itb = buckets_.at(index);
-          node_pointer n = itb->next;
           std::size_t count = 0;
-          while (n) {
-            ++count;
-            n = n->next;
+          if (size_ > 0) {
+            bucket_iterator itb = buckets_.at(index);
+            node_pointer n = itb->next;
+            while (n) {
+              ++count;
+              n = n->next;
+            }
           }
           return count;
         }
@@ -2420,11 +2422,14 @@
         node_pointer find_node_impl(
           Key const& x, bucket_iterator itb) const
         {
-          key_equal const& pred = this->key_eq();
-          node_pointer p = itb->next;
-          for (; p; p = p->next) {
-            if (pred(x, extractor::extract(p->value()))) {
-              break;
+          node_pointer p = node_pointer();
+          if (itb != buckets_.end()) {
+            key_equal const& pred = this->key_eq();
+            p = itb->next;
+            for (; p; p = p->next) {
+              if (pred(x, extractor::extract(p->value()))) {
+                break;
+              }
             }
           }
           return p;
@@ -2453,11 +2458,13 @@
         inline iterator transparent_find(
           Key const& k, Hash const& h, Pred const& pred) const
         {
-          std::size_t const key_hash = h(k);
-          bucket_iterator itb = buckets_.at(buckets_.position(key_hash));
-          for (node_pointer p = itb->next; p; p = p->next) {
-            if (BOOST_LIKELY(pred(k, extractor::extract(p->value())))) {
-              return iterator(p, itb);
+          if (size_ > 0) {
+            std::size_t const key_hash = h(k);
+            bucket_iterator itb = buckets_.at(buckets_.position(key_hash));
+            for (node_pointer p = itb->next; p; p = p->next) {
+              if (BOOST_LIKELY(pred(k, extractor::extract(p->value())))) {
+                return iterator(p, itb);
+              }
             }
           }
 
@@ -2467,11 +2474,13 @@
         template <class Key>
         node_pointer* find_prev(Key const& key, bucket_iterator itb)
         {
-          key_equal pred = this->key_eq();
-          for (node_pointer* pp = boost::addressof(itb->next); *pp;
-               pp = boost::addressof((*pp)->next)) {
-            if (pred(key, extractor::extract((*pp)->value()))) {
-              return pp;
+          if (size_ > 0) {
+            key_equal pred = this->key_eq();
+            for (node_pointer* pp = boost::addressof(itb->next); *pp;
+                pp = boost::addressof((*pp)->next)) {
+              if (pred(key, extractor::extract((*pp)->value()))) {
+                return pp;
+              }
             }
           }
           typedef node_pointer* node_pointer_pointer;
diff -urN boost_1_80_0/boost/unordered/unordered_map.hpp boost_1_80_1/boost/unordered/unordered_map.hpp
--- boost_1_80_0/boost/unordered/unordered_map.hpp	2022-08-03 22:47:16.000000000 -0400
+++ boost_1_80_1/boost/unordered/unordered_map.hpp	2022-08-24 19:44:43.139787681 -0400
@@ -2069,6 +2069,10 @@
     template <class K, class T, class H, class P, class A>
     float unordered_map<K, T, H, P, A>::load_factor() const BOOST_NOEXCEPT
     {
+      if (table_.size_ == 0) {
+        return 0.0f;
+      }
+
       BOOST_ASSERT(table_.bucket_count() != 0);
       return static_cast<float>(table_.size_) /
              static_cast<float>(table_.bucket_count());
@@ -2506,6 +2510,10 @@
     template <class K, class T, class H, class P, class A>
     float unordered_multimap<K, T, H, P, A>::load_factor() const BOOST_NOEXCEPT
     {
+      if (table_.size_ == 0) {
+        return 0.0f;
+      }
+
       BOOST_ASSERT(table_.bucket_count() != 0);
       return static_cast<float>(table_.size_) /
              static_cast<float>(table_.bucket_count());
diff -urN boost_1_80_0/boost/unordered/unordered_set.hpp boost_1_80_1/boost/unordered/unordered_set.hpp
--- boost_1_80_0/boost/unordered/unordered_set.hpp	2022-08-03 22:47:16.000000000 -0400
+++ boost_1_80_1/boost/unordered/unordered_set.hpp	2022-08-24 19:44:43.139787681 -0400
@@ -1586,6 +1586,10 @@
     template <class T, class H, class P, class A>
     float unordered_set<T, H, P, A>::load_factor() const BOOST_NOEXCEPT
     {
+      if (table_.size_ == 0) {
+        return 0.0f;
+      }
+
       BOOST_ASSERT(table_.bucket_count() != 0);
       return static_cast<float>(table_.size_) /
              static_cast<float>(table_.bucket_count());
@@ -1986,6 +1990,10 @@
     template <class T, class H, class P, class A>
     float unordered_multiset<T, H, P, A>::load_factor() const BOOST_NOEXCEPT
     {
+      if (table_.size_ == 0) {
+        return 0.0f;
+      }
+
       BOOST_ASSERT(table_.bucket_count() != 0);
       return static_cast<float>(table_.size_) /
              static_cast<float>(table_.bucket_count());