diff --git a/.dart_tool/package_config.json b/.dart_tool/package_config.json
index 7f75303304e..18b6a474629 100644
--- a/.dart_tool/package_config.json
+++ b/.dart_tool/package_config.json
@@ -11,7 +11,7 @@
     "constraint, update this by running tools/generate_package_config.dart."
   ],
   "configVersion": 2,
-  "generated": "2020-04-27T16:42:25.459210",
+  "generated": "2020-05-12T10:16:07.605273",
   "generator": "tools/generate_package_config.dart",
   "packages": [
     {
@@ -36,7 +36,7 @@
       "name": "analysis_server_client",
       "rootUri": "../pkg/analysis_server_client",
       "packageUri": "lib/",
-      "languageVersion": "2.1"
+      "languageVersion": "2.8"
     },
     {
       "name": "analysis_tool",
@@ -137,7 +137,7 @@
       "name": "crypto",
       "rootUri": "../third_party/pkg/crypto",
       "packageUri": "lib/",
-      "languageVersion": "2.0"
+      "languageVersion": "2.3"
     },
     {
       "name": "csslib",
@@ -191,7 +191,7 @@
       "name": "dartfix",
       "rootUri": "../pkg/dartfix",
       "packageUri": "lib/",
-      "languageVersion": "2.3"
+      "languageVersion": "2.8"
     },
     {
       "name": "dds",
@@ -254,6 +254,11 @@
       "rootUri": "../pkg/front_end/testcases/nnbd",
       "packageUri": ".nonexisting/"
     },
+    {
+      "name": "front_end_nnbd_mixed",
+      "rootUri": "../pkg/front_end/testcases/nnbd_mixed",
+      "packageUri": ".nonexisting/"
+    },
     {
       "name": "front_end_nonfunction_type_aliases",
       "rootUri": "../pkg/front_end/testcases/nonfunction_type_aliases",
@@ -305,7 +310,7 @@
       "name": "http_parser",
       "rootUri": "../third_party/pkg/http_parser",
       "packageUri": "lib/",
-      "languageVersion": "2.0"
+      "languageVersion": "2.3"
     },
     {
       "name": "http_retry",
@@ -585,7 +590,7 @@
       "name": "string_scanner",
       "rootUri": "../third_party/pkg/string_scanner",
       "packageUri": "lib/",
-      "languageVersion": "1.8"
+      "languageVersion": "2.0"
     },
     {
       "name": "telemetry",
diff --git a/tools/generate_package_config.dart b/tools/generate_package_config.dart
index 1833b6014ee..f43cdf7e499 100755
--- a/tools/generate_package_config.dart
+++ b/tools/generate_package_config.dart
@@ -31,6 +31,7 @@ void main(List<String> args) {
     packageDirectory('pkg/front_end/testcases/general_nnbd_opt_out/'),
     packageDirectory('pkg/front_end/testcases/late_lowering/'),
     packageDirectory('pkg/front_end/testcases/nnbd/'),
+    packageDirectory('pkg/front_end/testcases/nnbd_mixed/'),
     packageDirectory('pkg/front_end/testcases/nonfunction_type_aliases/'),
   ];
 
@@ -82,7 +83,9 @@ Iterable<Map<String, String>> makePackageConfigs(
 
     yield {
       'name': p.basename(packageDir),
-      'rootUri': p.relative(packageDir, from: p.dirname(configFilePath)),
+      'rootUri': p
+          .toUri(p.relative(packageDir, from: p.dirname(configFilePath)))
+          .toString(),
       if (hasLibDirectory) 'packageUri': 'lib/',
       if (version != null)
         'languageVersion': '${version.major}.${version.minor}'
@@ -97,7 +100,9 @@ Iterable<Map<String, String>> makeCfePackageConfigs(
   for (var packageDir in packageDirs) {
     yield {
       'name': 'front_end_${p.basename(packageDir)}',
-      'rootUri': p.relative(packageDir, from: p.dirname(configFilePath)),
+      'rootUri': p
+          .toUri(p.relative(packageDir, from: p.dirname(configFilePath)))
+          .toString(),
       'packageUri': '.nonexisting/',
     };
   }