diff --git a/app/protocol_filter.js b/app/protocol_filter.js
index 8889b2c11e..ba3b53b120 100644
--- a/app/protocol_filter.js
+++ b/app/protocol_filter.js
@@ -26,8 +26,25 @@ function _urlToPath(targetUrl, options = {}) {
 
 function _createFileHandler({ userDataPath, installPath, isWindows }) {
   return (request, callback) => {
+    let targetPath;
+    try {
+      targetPath = _urlToPath(request.url, { isWindows });
+    } catch (err) {
+      const errorMessage =
+        err && typeof err.message === 'string'
+          ? err.message
+          : 'no error message';
+      console.log(
+        `Warning: denying request because of an error: ${errorMessage}`
+      );
+
+      // This is an "invalid URL" error. See [Chromium's net error list][0].
+      //
+      // [0]: https://source.chromium.org/chromium/chromium/src/+/master:net/base/net_error_list.h;l=563;drc=a836ee9868cf1b9673fce362a82c98aba3e195de
+      return callback({ error: -300 });
+    }
     // normalize() is primarily useful here for switching / to \ on windows
-    const target = path.normalize(_urlToPath(request.url, { isWindows }));
+    const target = path.normalize(targetPath);
     // here we attempt to follow symlinks to the ultimate final path, reflective of what
     //   we do in main.js on userDataPath and installPath
     const realPath = fs.existsSync(target) ? fs.realpathSync(target) : target;
diff --git a/ts/components/CallBackgroundBlur.tsx b/ts/components/CallBackgroundBlur.tsx
index a085b3fc91..703bd8fb67 100644
--- a/ts/components/CallBackgroundBlur.tsx
+++ b/ts/components/CallBackgroundBlur.tsx
@@ -1,4 +1,4 @@
-// Copyright 2020 Signal Messenger, LLC
+// Copyright 2020-2021 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
 import React from 'react';
@@ -26,7 +26,7 @@ export const CallBackgroundBlur = ({
         <div
           className="module-calling__background--blur"
           style={{
-            backgroundImage: `url("${avatarPath}")`,
+            backgroundImage: `url('${encodeURI(avatarPath)}')`,
           }}
         />
       )}
diff --git a/ts/components/conversation/Quote.tsx b/ts/components/conversation/Quote.tsx
index 184278ea00..6002bec8fa 100644
--- a/ts/components/conversation/Quote.tsx
+++ b/ts/components/conversation/Quote.tsx
@@ -474,7 +474,7 @@ function ThumbnailImage({
     <div
       className="module-quote__icon-container"
       style={
-        loadedSrc ? { backgroundImage: `url('${escape(loadedSrc)}')` } : {}
+        loadedSrc ? { backgroundImage: `url('${encodeURI(loadedSrc)}')` } : {}
       }
     >
       {children}