diff --git a/browser/base/content/test/performance/PerfTestHelpers.jsm b/browser/base/content/test/performance/PerfTestHelpers.jsm
index bf5a1543f7ab..fd22a3aa6258 100644
--- a/browser/base/content/test/performance/PerfTestHelpers.jsm
+++ b/browser/base/content/test/performance/PerfTestHelpers.jsm
@@ -50,6 +50,9 @@ var PerfTestHelpers = {
         let channel = lazy.NetUtil.newChannel({
           uri,
           loadUsingSystemPrincipal: true,
+          // Avoid crashing for non-existant files. If the file not existing
+          // is bad, we can deal with it in the test instead.
+          contentPolicyType: Ci.nsIContentPolicy.TYPE_FETCH,
         });
 
         channel.asyncOpen({
diff --git a/modules/libjar/nsJARChannel.cpp b/modules/libjar/nsJARChannel.cpp
index 6d8b9e4473a0..8e3a057cc4b7 100644
--- a/modules/libjar/nsJARChannel.cpp
+++ b/modules/libjar/nsJARChannel.cpp
@@ -286,9 +286,6 @@ nsresult nsJARChannel::CreateJarInput(nsIZipReaderCache* jarCache,
       new nsJARInputThunk(reader, mJarURI, mJarEntry, jarCache != nullptr);
   rv = input->Init();
   if (NS_FAILED(rv)) {
-    if (rv == NS_ERROR_FILE_NOT_FOUND) {
-      CheckForBrokenChromeURL(mLoadInfo, mOriginalURI);
-    }
     return rv;
   }
 
@@ -488,6 +485,9 @@ nsresult nsJARChannel::OnOpenLocalFileComplete(nsresult aResult,
   MOZ_ASSERT(mIsPending);
 
   if (NS_FAILED(aResult)) {
+    if (aResult == NS_ERROR_FILE_NOT_FOUND) {
+      CheckForBrokenChromeURL(mLoadInfo, mOriginalURI);
+    }
     if (!aIsSyncCall) {
       NotifyError(aResult);
     }
diff --git a/netwerk/base/nsNetUtil.cpp b/netwerk/base/nsNetUtil.cpp
index fcb887140094..bdad496d2e70 100644
--- a/netwerk/base/nsNetUtil.cpp
+++ b/netwerk/base/nsNetUtil.cpp
@@ -3864,6 +3864,20 @@ void CheckForBrokenChromeURL(nsILoadInfo* aLoadInfo, nsIURI* aURI) {
   nsCString spec;
   aURI->GetSpec(spec);
 
+#ifdef ANDROID
+  // Various toolkit files use this and are shipped on android, but
+  // info-pages.css and aboutLicense.css are not - bug 1808987
+  if (StringEndsWith(spec, "info-pages.css"_ns) ||
+      StringEndsWith(spec, "aboutLicense.css"_ns) ||
+      // Error page CSS is also missing: bug 1810039
+      StringEndsWith(spec, "aboutNetError.css"_ns) ||
+      StringEndsWith(spec, "error-pages.css"_ns) ||
+      // Used by an extension installation test - bug 1809650
+      StringBeginsWith(spec, "resource://android/assets/web_extensions/"_ns)) {
+    return;
+  }
+#endif
+
   // DTD files from gre may not exist when requested by tests.
   if (StringBeginsWith(spec, "resource://gre/res/dtd/"_ns)) {
     return;