diff --git a/HISTORY.md b/HISTORY.md
index fc7b72d9..efa51905 100755
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -8,9 +8,10 @@
     * web-serial support, thanks, Dariusz Dorożalski!
     * hide custom helper blocks in palette
 * **Notable Changes:**
-    * saved projects remember the last edited srpite
+    * saved projects remember the last edited sprite
     * libraries no longer rely on the JSF primitive, project may need to re-import their libraries to run without having to enable JS extensions
     * retired Leap Motion library, took out Hummingbird library (get the current one from Birdbrain)
+    * display blocks with their error messages for custom blocks, thanks, Michael!
 * **Notable Fixes:**
     * made scrollbars in the wardrobe and jukebox more responsive
     * fixed centering of menus, thanks, Brian Broll!
@@ -22,6 +23,7 @@
 ### 2021-07-07
 * morphic, gui: tweaked perish() animation
 * objects: fixed "hide / show primitives" for unified palette
+* threads: display blocks with their error messages for custom blocks, thanks, Michael!
 
 ### 2021-07-06
 * byob, objects: new feature: hide custom helper blocks in palette
diff --git a/snap.html b/snap.html
index 4f085f11..cdc02b9c 100755
--- a/snap.html
+++ b/snap.html
@@ -9,7 +9,7 @@
         <script src="src/symbols.js?version=2021-03-03"></script>
         <script src="src/widgets.js?version=2021-07-05"></script>
         <script src="src/blocks.js?version=2021-07-05"></script>
-        <script src="src/threads.js?version=2021-07-05"></script>
+        <script src="src/threads.js?version=2021-07-07"></script>
         <script src="src/objects.js?version=2021-07-07"></script>
         <script src="src/scenes.js?version=2021-07-06"></script>
         <script src="src/gui.js?version=2021-07-07"></script>
diff --git a/src/threads.js b/src/threads.js
index 249e4047..9d512291 100644
--- a/src/threads.js
+++ b/src/threads.js
@@ -60,11 +60,11 @@ IDE_Morph, ArgLabelMorph, localize, XML_Element, hex_sha512, TableDialogMorph,
 StageMorph, SpriteMorph, StagePrompterMorph, Note, modules, isString, copy, Map,
 isNil, WatcherMorph, List, ListWatcherMorph, alert, console, TableMorph, BLACK,
 TableFrameMorph, ColorSlotMorph, isSnapObject, newCanvas, Symbol, SVG_Costume,
-SnapExtensions*/
+SnapExtensions, AlignmentMorph, TextMorph*/
 
 /*jshint esversion: 6*/
 
-modules.threads = '2021-July-05';
+modules.threads = '2021-July-07';
 
 var ThreadManager;
 var Process;
@@ -1176,7 +1176,8 @@ Process.prototype.errorBubble = function (error, element) {
     // above the text of error.
     var errorMorph = new AlignmentMorph('column', 5),
         errorIsNested = isNil(element.world()),
-        errorPrefix = errorIsNested ? `${localize('Inside a custom block')}:\n`: '',
+        errorPrefix = errorIsNested ? `${localize('Inside a custom block')}:\n`
+            : '',
         errorMessage = new TextMorph(
             `${errorPrefix}${localize(error.name)}:\n${localize(error.message)}`,
             SyntaxElementMorph.prototype.fontSize
@@ -1195,7 +1196,7 @@ Process.prototype.errorBubble = function (error, element) {
     }
 
     return errorMorph;
-}
+};
 
 // Process Lambda primitives