diff --git a/CHANGELOG.MD b/CHANGELOG.MD
index d5bcc90ce..e68802dce 100644
--- a/CHANGELOG.MD
+++ b/CHANGELOG.MD
@@ -1,5 +1,12 @@
 # Change Log
 
+
+## Version 3.8.1 - Nov 1, 2020
+
+### Fixed
+
+* Fixes atlas thumbnail generation when atlas URL is pointing to a missing file.
+
 ## Version 3.8.0 - Oct 30, 2020
 
 ### Added
diff --git a/source/editor/plugins/phasereditor2d.ide/src/IDEPlugin.ts b/source/editor/plugins/phasereditor2d.ide/src/IDEPlugin.ts
index 4fd25bec4..c46c18bb1 100644
--- a/source/editor/plugins/phasereditor2d.ide/src/IDEPlugin.ts
+++ b/source/editor/plugins/phasereditor2d.ide/src/IDEPlugin.ts
@@ -289,7 +289,7 @@ namespace phasereditor2d.ide {
 
     /* program entry point */
 
-    export const VER = "3.8.0";
+    export const VER = "3.8.1";
 
     async function main() {
 
diff --git a/source/editor/plugins/phasereditor2d.pack/src/core/AssetPackItem.ts b/source/editor/plugins/phasereditor2d.pack/src/core/AssetPackItem.ts
index 15b537081..b7345b603 100644
--- a/source/editor/plugins/phasereditor2d.pack/src/core/AssetPackItem.ts
+++ b/source/editor/plugins/phasereditor2d.pack/src/core/AssetPackItem.ts
@@ -46,8 +46,13 @@ namespace phasereditor2d.pack.core {
         protected addFilesFromUrls(files: Set<io.FilePath>, urls: string[]) {
 
             for (const url of urls) {
+
                 const file = AssetPackUtils.getFileFromPackUrl(url);
-                files.add(file);
+
+                if (file) {
+
+                    files.add(file);
+                }
             }
         }
 
diff --git a/source/editor/plugins/phasereditor2d.pack/src/core/ImageFrameContainerAssetPackItem.ts b/source/editor/plugins/phasereditor2d.pack/src/core/ImageFrameContainerAssetPackItem.ts
index 96a5f1df0..d907af48f 100644
--- a/source/editor/plugins/phasereditor2d.pack/src/core/ImageFrameContainerAssetPackItem.ts
+++ b/source/editor/plugins/phasereditor2d.pack/src/core/ImageFrameContainerAssetPackItem.ts
@@ -65,7 +65,11 @@ namespace phasereditor2d.pack.core {
 
             this.computeUsedFiles(files);
 
-            const key = [...files].map(file => file.getFullName() + "@" + file.getModTime()).join(",");
+            const key = [...files]
+
+                .filter(file => file !== null && file !== undefined)
+
+                .map(file => file.getFullName() + "@" + file.getModTime()).join(",");
 
             return key;
         }
diff --git a/source/editor/plugins/phasereditor2d.pack/src/core/MultiAtlasAssetPackItem.ts b/source/editor/plugins/phasereditor2d.pack/src/core/MultiAtlasAssetPackItem.ts
index ded2dbb1d..96ff5599d 100644
--- a/source/editor/plugins/phasereditor2d.pack/src/core/MultiAtlasAssetPackItem.ts
+++ b/source/editor/plugins/phasereditor2d.pack/src/core/MultiAtlasAssetPackItem.ts
@@ -2,7 +2,6 @@ namespace phasereditor2d.pack.core {
 
     import io = colibri.core.io;
     import ide = colibri.ui.ide;
-    import controls = colibri.ui.controls;
 
     export class MultiatlasAssetPackItem extends BaseAtlasAssetPackItem {