diff --git a/bin/build-site.sh b/bin/build-site.sh
index f6cc2dfea..5cb0d13a3 100755
--- a/bin/build-site.sh
+++ b/bin/build-site.sh
@@ -5,7 +5,7 @@
 # Default to the current version number for building the plugin library
 
 if [  -z "$TW5_BUILD_VERSION" ]; then
-    TW5_BUILD_VERSION=v5.1.19
+    TW5_BUILD_VERSION=v5.1.20
 fi
 
 echo "Using TW5_BUILD_VERSION as [$TW5_BUILD_VERSION]"
diff --git a/core/wiki/config/OfficialPluginLibrary.tid b/core/wiki/config/OfficialPluginLibrary.tid
index b43c69610..f2ed50c1f 100644
--- a/core/wiki/config/OfficialPluginLibrary.tid
+++ b/core/wiki/config/OfficialPluginLibrary.tid
@@ -1,6 +1,6 @@
 title: $:/config/OfficialPluginLibrary
 tags: $:/tags/PluginLibrary
-url: https://tiddlywiki.com/library/v5.1.20/index.html
+url: https://tiddlywiki.com/library/v5.1.21/index.html
 caption: {{$:/language/OfficialPluginLibrary}}
 
 {{$:/language/OfficialPluginLibrary/Hint}}
diff --git a/editions/dev/tiddlers/build/Releasing a new version of TiddlyWiki.tid b/editions/dev/tiddlers/build/Releasing a new version of TiddlyWiki.tid
index f0228bb7e..f20b8fcae 100644
--- a/editions/dev/tiddlers/build/Releasing a new version of TiddlyWiki.tid	
+++ b/editions/dev/tiddlers/build/Releasing a new version of TiddlyWiki.tid	
@@ -39,6 +39,7 @@ type: text/vnd.tiddlywiki
 # Adjust version number in `package.json`
 # Adjust version number in `bin/build-site.sh`
 # Adjust version number in [[$:/config/OfficialPluginLibrary]] (both in `editions/tw5.com` and `editions/prerelease/tiddlers/system`) and [[$:/config/LocalPluginLibrary]]
+# Adjust new release banner
 # Create the release note for the new release
 # Adjust version number in https://github.com/Jermolene/build.jermolene.github.io in `prerelease-bld.sh`, `bld.sh` and `make-library-bld.sh`
 # Commit changes to ''master'' and push to ~GitHub
diff --git a/editions/prerelease/tiddlers/Release 5.1.21.tid b/editions/prerelease/tiddlers/Release 5.1.21.tid
new file mode 100644
index 000000000..2aca5e6a2
--- /dev/null
+++ b/editions/prerelease/tiddlers/Release 5.1.21.tid	
@@ -0,0 +1,50 @@
+caption: 5.1.21
+created: 20190809153802329
+modified: 20190809153802329
+tags: ReleaseNotes
+title: Release 5.1.21
+type: text/vnd.tiddlywiki
+
+//[[See GitHub for detailed change history of this release|https://github.com/Jermolene/TiddlyWiki5/compare/v5.1.20...v5.1.21]]//
+
+!! Plugin Improvements
+
+New and improved plugins:
+
+* 
+
+!! Translation Improvements
+
+New and improved translations:
+
+* 
+
+!! Performance Improvements
+
+* 
+
+!! Usability Improvements
+
+* 
+
+!! Hackability Improvements
+
+* 
+
+!! Bug Fixes
+
+* 
+
+!! Node.js Bug Fixes and Improvements
+
+* 
+
+!! Developer Bug Fixes and Improvements
+
+* 
+
+! Contributors
+
+[[@Jermolene|https://github.com/Jermolene]] would like to thank the contributors to this release who have generously given their time to help improve TiddlyWiki:
+
+* 
diff --git a/editions/prerelease/tiddlers/system/PrereleaseLocalPluginLibrary.tid b/editions/prerelease/tiddlers/system/PrereleaseLocalPluginLibrary.tid
index 88301fd3e..6b3ecb0f9 100644
--- a/editions/prerelease/tiddlers/system/PrereleaseLocalPluginLibrary.tid
+++ b/editions/prerelease/tiddlers/system/PrereleaseLocalPluginLibrary.tid
@@ -1,6 +1,6 @@
 title: $:/config/LocalPluginLibrary
 tags: $:/tags/PluginLibrary
-url: http://127.0.0.1:8080/prerelease/library/v5.1.20/index.html
+url: http://127.0.0.1:8080/prerelease/library/v5.1.21/index.html
 caption: {{$:/language/OfficialPluginLibrary}} (Prerelease Local)
 
 A locally installed version of the official ~TiddlyWiki plugin library at tiddlywiki.com for testing and debugging. //Requires a local web server to share the library//
diff --git a/editions/prerelease/tiddlers/system/PrereleaseOfficialPluginLibrary.tid b/editions/prerelease/tiddlers/system/PrereleaseOfficialPluginLibrary.tid
index 7a687e363..63029fddc 100644
--- a/editions/prerelease/tiddlers/system/PrereleaseOfficialPluginLibrary.tid
+++ b/editions/prerelease/tiddlers/system/PrereleaseOfficialPluginLibrary.tid
@@ -1,6 +1,6 @@
 title: $:/config/OfficialPluginLibrary
 tags: $:/tags/PluginLibrary
-url: https://tiddlywiki.com/prerelease/library/v5.1.20/index.html
+url: https://tiddlywiki.com/prerelease/library/v5.1.21/index.html
 caption: {{$:/language/OfficialPluginLibrary}} (Prerelease)
 
 The prerelease version of the official ~TiddlyWiki plugin library at tiddlywiki.com. Plugins, themes and language packs are maintained by the core team.
diff --git a/editions/tw5.com/tiddlers/images/New Release Banner.jpg b/editions/tw5.com/tiddlers/images/New Release Banner.jpg
index dd31b43f0..98cd72519 100644
Binary files a/editions/tw5.com/tiddlers/images/New Release Banner.jpg and b/editions/tw5.com/tiddlers/images/New Release Banner.jpg differ
diff --git a/package.json b/package.json
index d9c17b57c..d05ad4db1 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "tiddlywiki",
   "preferGlobal": "true",
-  "version": "5.1.20",
+  "version": "5.1.21-prerelease",
   "author": "Jeremy Ruston <jeremy@jermolene.com>",
   "description": "a non-linear personal web notebook",
   "contributors": [