diff --git a/.all-contributorsrc b/.all-contributorsrc
index fe18385f..cda03778 100644
--- a/.all-contributorsrc
+++ b/.all-contributorsrc
@@ -1020,6 +1020,24 @@
       "contributions": [
         "content"
       ]
+    },
+    {
+      "login": "xuesongbj",
+      "name": "xuesong",
+      "avatar_url": "https://avatars.githubusercontent.com/u/18476085?v=4",
+      "profile": "http://xuesong.pydevops.com",
+      "contributions": [
+        "content"
+      ]
+    },
+    {
+      "login": "MpdWalsh",
+      "name": "Michael Walsh",
+      "avatar_url": "https://avatars.githubusercontent.com/u/48160144?v=4",
+      "profile": "https://github.com/MpdWalsh",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "contributorsPerLine": 8,
diff --git a/Cargo.toml b/Cargo.toml
index 3b2a85a7..30032695 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,7 +2,7 @@
 name = "rustlings"
 version = "4.6.0"
 authors = ["anastasie <ana@ana.st>", "Carol (Nichols || Goulding) <carol.nichols@gmail.com>"]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 argh = "0.1.4"
diff --git a/README.md b/README.md
index 6e5ce3f6..c0ba6ce9 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,5 @@
 <!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
-[![All Contributors](https://img.shields.io/badge/all_contributors-110-orange.svg?style=flat-square)](#contributors-)
+[![All Contributors](https://img.shields.io/badge/all_contributors-112-orange.svg?style=flat-square)](#contributors-)
 <!-- ALL-CONTRIBUTORS-BADGE:END -->
 
 # rustlings 🦀❤️
@@ -314,6 +314,8 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
     <td align="center"><a href="https://frogtd.com/"><img src="https://avatars.githubusercontent.com/u/31412003?v=4?s=100" width="100px;" alt=""/><br /><sub><b>frogtd</b></sub></a><br /><a href="#content-frogtd" title="Content">🖋</a></td>
     <td align="center"><a href="https://github.com/EmisonLu"><img src="https://avatars.githubusercontent.com/u/54395432?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Zhenghao Lu</b></sub></a><br /><a href="#content-EmisonLu" title="Content">🖋</a></td>
     <td align="center"><a href="https://soundtrackyourbrand.com"><img src="https://avatars.githubusercontent.com/u/762956?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Fredrik Enestad</b></sub></a><br /><a href="#content-fredr" title="Content">🖋</a></td>
+    <td align="center"><a href="http://xuesong.pydevops.com"><img src="https://avatars.githubusercontent.com/u/18476085?v=4?s=100" width="100px;" alt=""/><br /><sub><b>xuesong</b></sub></a><br /><a href="#content-xuesongbj" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/MpdWalsh"><img src="https://avatars.githubusercontent.com/u/48160144?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Michael Walsh</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=MpdWalsh" title="Code">💻</a></td>
   </tr>
 </table>
 
diff --git a/exercises/advanced_errors/advanced_errs2.rs b/exercises/advanced_errors/advanced_errs2.rs
index d9d44d06..54e669fd 100644
--- a/exercises/advanced_errors/advanced_errs2.rs
+++ b/exercises/advanced_errors/advanced_errs2.rs
@@ -64,7 +64,6 @@ impl Display for ParseClimateError {
         match self {
             NoCity => write!(f, "no city name"),
             ParseFloat(e) => write!(f, "error parsing temperature: {}", e),
-            _ => write!(f, "unhandled error!"),
         }
     }
 }
diff --git a/exercises/traits/traits1.rs b/exercises/traits/traits1.rs
index d17909d5..d6391db7 100644
--- a/exercises/traits/traits1.rs
+++ b/exercises/traits/traits1.rs
@@ -30,12 +30,12 @@ mod tests {
     use super::*;
 
     #[test]
-    fn is_FooBar() {
+    fn is_foo_bar() {
         assert_eq!(String::from("Foo").append_bar(), String::from("FooBar"));
     }
 
     #[test]
-    fn is_BarBar() {
+    fn is_bar_bar() {
         assert_eq!(
             String::from("").append_bar().append_bar(),
             String::from("BarBar")