diff -Nru ccache-4.5/cmake/CcacheVersion.cmake ccache-4.5.1/cmake/CcacheVersion.cmake
--- ccache-4.5/cmake/CcacheVersion.cmake	2021-11-13 09:42:24.000000000 +0000
+++ ccache-4.5.1/cmake/CcacheVersion.cmake	2021-11-17 19:31:58.000000000 +0000
@@ -22,7 +22,7 @@
 # CCACHE_VERSION_ORIGIN is set to "archive" in scenario 1 and "git" in scenario
 # 3.
 
-set(version_info "6eedb905a1a21fc8a6399b030312def2c510560c HEAD, tag: v4.5, origin/master, origin/HEAD, master")
+set(version_info "764dc83795d9a05c2a9d69f267ed86f61a253d09 HEAD, tag: v4.5.1, origin/HEAD, origin/4.5-maint, 4.5-maint")
 
 if(version_info MATCHES "^([0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f])[0-9a-f]* (.*)")
   # Scenario 1.
diff -Nru ccache-4.5/debian/changelog ccache-4.5.1/debian/changelog
--- ccache-4.5/debian/changelog	2021-11-13 15:05:58.000000000 +0000
+++ ccache-4.5.1/debian/changelog	2021-11-17 19:59:25.000000000 +0000
@@ -1,3 +1,9 @@
+ccache (4.5.1-1) unstable; urgency=medium
+
+  * New upstream release 4.5.1
+
+ -- Joel Rosdahl <joel@debian.org>  Wed, 17 Nov 2021 20:59:25 +0100
+
 ccache (4.5-1) unstable; urgency=medium
 
   * Refer to common license file for CC0-1.0
diff -Nru ccache-4.5/doc/NEWS.adoc ccache-4.5.1/doc/NEWS.adoc
--- ccache-4.5/doc/NEWS.adoc	2021-11-13 09:42:24.000000000 +0000
+++ ccache-4.5.1/doc/NEWS.adoc	2021-11-17 19:31:58.000000000 +0000
@@ -1,5 +1,25 @@
 = Ccache news
 
+== Ccache 4.5.1
+
+Release date: 2021-11-17
+
+
+=== Bug fixes
+
+- Fixed entry_size field for result entries. This bug affected the recompression
+  feature (`-X`/`--recompress`) in ccache 4.5. +
+  [small]#_[contributed by Joel Rosdahl]_#
+
+- The actual compression level is now once again stored in the cache entry
+  header. +
+  [small]#_[contributed by Joel Rosdahl]_#
+
+- Corrected error handling for unconstructible secondary storage backends. For
+  instance, this avoids a crash when a Redis server can't be reached. +
+  [small]#_[contributed by Joel Rosdahl]_#
+
+
 == Ccache 4.5
 
 Release date: 2021-11-13
diff -Nru ccache-4.5/src/core/CacheEntryWriter.cpp ccache-4.5.1/src/core/CacheEntryWriter.cpp
--- ccache-4.5/src/core/CacheEntryWriter.cpp	2021-11-13 09:42:24.000000000 +0000
+++ ccache-4.5.1/src/core/CacheEntryWriter.cpp	2021-11-17 19:31:58.000000000 +0000
@@ -33,7 +33,7 @@
   m_checksumming_writer.write_int(static_cast<uint8_t>(header.entry_type));
   m_checksumming_writer.write_int(
     static_cast<uint8_t>(header.compression_type));
-  m_checksumming_writer.write_int(header.compression_level);
+  m_checksumming_writer.write_int(m_compressor->actual_compression_level());
   m_checksumming_writer.write_int(header.creation_time);
   m_checksumming_writer.write_int<uint8_t>(header.ccache_version.length());
   m_checksumming_writer.write_str(header.ccache_version);
diff -Nru ccache-4.5/src/Result.cpp ccache-4.5.1/src/Result.cpp
--- ccache-4.5/src/Result.cpp	2021-11-13 09:42:24.000000000 +0000
+++ ccache-4.5.1/src/Result.cpp	2021-11-17 19:31:58.000000000 +0000
@@ -325,6 +325,7 @@
 {
   FileSizeAndCountDiff file_size_and_count_diff{0, 0};
   uint64_t payload_size = 0;
+  payload_size += 1; // format_ver
   payload_size += 1; // n_entries
   for (const auto& pair : m_entries_to_write) {
     const auto& path = pair.second;
diff -Nru ccache-4.5/src/storage/secondary/FileStorage.cpp ccache-4.5.1/src/storage/secondary/FileStorage.cpp
--- ccache-4.5/src/storage/secondary/FileStorage.cpp	2021-11-13 09:42:24.000000000 +0000
+++ ccache-4.5.1/src/storage/secondary/FileStorage.cpp	2021-11-17 19:31:58.000000000 +0000
@@ -70,7 +70,7 @@
   ASSERT(params.url.scheme() == "file");
   if (!params.url.host().empty()) {
     throw core::Fatal(FMT(
-      "invalid file path \"{}\":  specifying a host (\"{}\") is not supported",
+      "invalid file path \"{}\": specifying a host (\"{}\") is not supported",
       params.url.str(),
       params.url.host()));
   }
diff -Nru ccache-4.5/src/storage/Storage.cpp ccache-4.5.1/src/storage/Storage.cpp
--- ccache-4.5/src/storage/Storage.cpp	2021-11-13 09:42:24.000000000 +0000
+++ ccache-4.5.1/src/storage/Storage.cpp	2021-11-17 19:31:58.000000000 +0000
@@ -450,6 +450,7 @@
           entry.url_for_logging,
           nonstd::string_view(e.what()).empty() ? "" : FMT(": {}", e.what()));
       mark_backend_as_failed(entry.backends.back(), e.failure());
+      return nullptr;
     }
     return &entry.backends.back();
   } else if (backend->failed) {
diff -Nru ccache-4.5/test/suites/secondary_redis.bash ccache-4.5.1/test/suites/secondary_redis.bash
--- ccache-4.5/test/suites/secondary_redis.bash	2021-11-13 09:42:24.000000000 +0000
+++ ccache-4.5.1/test/suites/secondary_redis.bash	2021-11-17 19:31:58.000000000 +0000
@@ -111,4 +111,15 @@
     expect_stat cache_miss 1
     expect_stat files_in_cache 2 # fetched from secondary
     expect_number_of_redis_cache_entries 2 "$redis_url" # result + manifest
+
+    # -------------------------------------------------------------------------
+    TEST "Unreachable server"
+
+    export CCACHE_SECONDARY_STORAGE="redis://localhost:1"
+
+    $CCACHE_COMPILE -c test.c
+    expect_stat direct_cache_hit 0
+    expect_stat cache_miss 1
+    expect_stat files_in_cache 2
+    expect_stat secondary_storage_error 1
 }