diff --git a/cli/emit.rs b/cli/emit.rs
index a4713f5322..07b6398bb8 100644
--- a/cli/emit.rs
+++ b/cli/emit.rs
@@ -160,8 +160,6 @@ pub(crate) fn get_ts_config(
         "target": "esnext",
         "tsBuildInfoFile": "deno:///.tsbuildinfo",
         "useDefineForClassFields": true,
-        // TODO(@kitsonk) remove for Deno 2.0
-        "useUnknownInCatchVariables": false,
       }));
       if tsc_emit {
         ts_config.merge(&json!({
@@ -213,8 +211,6 @@ pub(crate) fn get_ts_config(
         "target": "esnext",
         "tsBuildInfoFile": "deno:///.tsbuildinfo",
         "useDefineForClassFields": true,
-        // TODO(@kitsonk) remove for Deno 2.0
-        "useUnknownInCatchVariables": false,
       }));
       if tsc_emit {
         ts_config.merge(&json!({
diff --git a/cli/lsp/language_server.rs b/cli/lsp/language_server.rs
index c5de984ad5..13fcafec15 100644
--- a/cli/lsp/language_server.rs
+++ b/cli/lsp/language_server.rs
@@ -629,8 +629,6 @@ impl Inner {
       "strict": true,
       "target": "esnext",
       "useDefineForClassFields": true,
-      // TODO(@kitsonk) remove for Deno 1.15
-      "useUnknownInCatchVariables": false,
     }));
     let config = &self.config;
     let workspace_settings = config.get_workspace_settings();
diff --git a/cli/tests/integration/run_tests.rs b/cli/tests/integration/run_tests.rs
index d4e7ccf723..ec42a8dc8f 100644
--- a/cli/tests/integration/run_tests.rs
+++ b/cli/tests/integration/run_tests.rs
@@ -1367,6 +1367,13 @@ itest!(error_import_map_unable_to_load {
   exit_code: 1,
 });
 
+// This test ensure that useUnknownInCatchVariables is enabled by default.
+itest!(use_unknown_in_catch_variables {
+  args: "run useUnknownInCatchVariables.ts",
+  output: "useUnknownInCatchVariables.ts.out",
+  exit_code: 1,
+});
+
 // Test that setting `self` in the main thread to some other value doesn't break
 // the world.
 itest!(replace_self {
diff --git a/cli/tests/testdata/070_location.ts b/cli/tests/testdata/070_location.ts
index 61256dcbcf..149de54230 100644
--- a/cli/tests/testdata/070_location.ts
+++ b/cli/tests/testdata/070_location.ts
@@ -4,5 +4,7 @@ console.log(location);
 try {
   location.hostname = "bar";
 } catch (error) {
-  console.log(error.toString());
+  if (error instanceof Error) {
+    console.log(error.toString());
+  }
 }
diff --git a/cli/tests/testdata/085_dynamic_import_async_error.ts b/cli/tests/testdata/085_dynamic_import_async_error.ts
index aa5ff7277e..998e7ed3e4 100644
--- a/cli/tests/testdata/085_dynamic_import_async_error.ts
+++ b/cli/tests/testdata/085_dynamic_import_async_error.ts
@@ -1,5 +1,7 @@
 try {
   await import("./delayed_error.ts");
 } catch (error) {
-  console.log(`Caught: ${error.stack}`);
+  if (error instanceof Error) {
+    console.log(`Caught: ${error.stack}`);
+  }
 }
diff --git a/cli/tests/testdata/086_dynamic_import_already_rejected.ts b/cli/tests/testdata/086_dynamic_import_already_rejected.ts
index 359db670c3..249de8d8b4 100644
--- a/cli/tests/testdata/086_dynamic_import_already_rejected.ts
+++ b/cli/tests/testdata/086_dynamic_import_already_rejected.ts
@@ -1,11 +1,15 @@
 try {
   await import("./error_001.ts");
 } catch (error) {
-  console.log(`Caught: ${error.stack}`);
+  if (error instanceof Error) {
+    console.log(`Caught: ${error.stack}`);
+  }
 }
 
 try {
   await import("./error_001.ts");
 } catch (error) {
-  console.log(`Caught: ${error.stack}`);
+  if (error instanceof Error) {
+    console.log(`Caught: ${error.stack}`);
+  }
 }
diff --git a/cli/tests/testdata/error_019_stack_function.ts b/cli/tests/testdata/error_019_stack_function.ts
index c5eeae8f4a..a6a69d146e 100644
--- a/cli/tests/testdata/error_019_stack_function.ts
+++ b/cli/tests/testdata/error_019_stack_function.ts
@@ -5,6 +5,8 @@ function foo(): never {
 try {
   foo();
 } catch (error) {
-  console.log(error.stack);
+  if (error instanceof Error) {
+    console.log(error.stack);
+  }
   throw error;
 }
diff --git a/cli/tests/testdata/error_020_stack_constructor.ts b/cli/tests/testdata/error_020_stack_constructor.ts
index 49988280b1..526d1a661f 100644
--- a/cli/tests/testdata/error_020_stack_constructor.ts
+++ b/cli/tests/testdata/error_020_stack_constructor.ts
@@ -7,6 +7,8 @@ class A {
 try {
   new A();
 } catch (error) {
-  console.log(error.stack);
+  if (error instanceof Error) {
+    console.log(error.stack);
+  }
   throw error;
 }
diff --git a/cli/tests/testdata/error_021_stack_method.ts b/cli/tests/testdata/error_021_stack_method.ts
index a52d00deb6..b6ebe1f5ec 100644
--- a/cli/tests/testdata/error_021_stack_method.ts
+++ b/cli/tests/testdata/error_021_stack_method.ts
@@ -7,6 +7,8 @@ class A {
 try {
   new A().m();
 } catch (error) {
-  console.log(error.stack);
+  if (error instanceof Error) {
+    console.log(error.stack);
+  }
   throw error;
 }
diff --git a/cli/tests/testdata/error_023_stack_async.ts b/cli/tests/testdata/error_023_stack_async.ts
index 99e676e26d..fdabaa5df1 100644
--- a/cli/tests/testdata/error_023_stack_async.ts
+++ b/cli/tests/testdata/error_023_stack_async.ts
@@ -7,6 +7,8 @@ const p = (async () => {
 try {
   await p;
 } catch (error) {
-  console.log(error.stack);
+  if (error instanceof Error) {
+    console.log(error.stack);
+  }
   throw error;
 }
diff --git a/cli/tests/testdata/error_024_stack_promise_all.ts b/cli/tests/testdata/error_024_stack_promise_all.ts
index ddaf0dbaab..8ca7b203c9 100644
--- a/cli/tests/testdata/error_024_stack_promise_all.ts
+++ b/cli/tests/testdata/error_024_stack_promise_all.ts
@@ -9,6 +9,8 @@ const p = Promise.all([
 try {
   await p;
 } catch (error) {
-  console.log(error.stack);
+  if (error instanceof Error) {
+    console.log(error.stack);
+  }
   throw error;
 }
diff --git a/cli/tests/testdata/resolve_dns.ts b/cli/tests/testdata/resolve_dns.ts
index e4a50f7dc8..1757c938ef 100644
--- a/cli/tests/testdata/resolve_dns.ts
+++ b/cli/tests/testdata/resolve_dns.ts
@@ -38,5 +38,9 @@ console.log(JSON.stringify(txt));
 try {
   await Deno.resolveDns("not-found-example.com", "A", nameServer);
 } catch (e) {
-  console.log(`Error ${e.name} thrown for not-found-example.com`);
+  console.log(
+    `Error ${
+      e instanceof Error ? e.name : "[non-error]"
+    } thrown for not-found-example.com`,
+  );
 }
diff --git a/cli/tests/testdata/useUnknownInCatchVariables.ts b/cli/tests/testdata/useUnknownInCatchVariables.ts
new file mode 100644
index 0000000000..abab554a43
--- /dev/null
+++ b/cli/tests/testdata/useUnknownInCatchVariables.ts
@@ -0,0 +1,5 @@
+try {
+  throw new Error();
+} catch (e) {
+  console.log(e.message);
+}
diff --git a/cli/tests/testdata/useUnknownInCatchVariables.ts.out b/cli/tests/testdata/useUnknownInCatchVariables.ts.out
new file mode 100644
index 0000000000..3c29d3229d
--- /dev/null
+++ b/cli/tests/testdata/useUnknownInCatchVariables.ts.out
@@ -0,0 +1,5 @@
+[WILDCARD]
+error: TS2571 [ERROR]: Object is of type 'unknown'.
+  console.log(e.message);
+              ^
+    at file://[WILDCARD]/useUnknownInCatchVariables.ts:4:15
diff --git a/cli/tests/unit/opcall_test.ts b/cli/tests/unit/opcall_test.ts
index 7e36853208..e38f481d99 100644
--- a/cli/tests/unit/opcall_test.ts
+++ b/cli/tests/unit/opcall_test.ts
@@ -12,7 +12,9 @@ unitTest(async function sendAsyncStackTrace() {
     await Deno.read(rid, buf);
     unreachable();
   } catch (error) {
-    const s = error.stack.toString();
+    assert(error instanceof Error);
+    const s = error.stack?.toString();
+    assert(s);
     console.log(s);
     assertStringIncludes(s, "opcall_test.ts");
     assertStringIncludes(s, "read");
diff --git a/cli/tests/unit/text_encoding_test.ts b/cli/tests/unit/text_encoding_test.ts
index a65a4176bd..d83d845848 100644
--- a/cli/tests/unit/text_encoding_test.ts
+++ b/cli/tests/unit/text_encoding_test.ts
@@ -98,6 +98,7 @@ unitTest(function textDecoderErrorEncoding() {
     new TextDecoder("Foo");
   } catch (e) {
     didThrow = true;
+    assert(e instanceof Error);
     assertEquals(e.message, "The encoding label provided ('Foo') is invalid.");
   }
   assert(didThrow);
diff --git a/cli/tests/unit/write_file_test.ts b/cli/tests/unit/write_file_test.ts
index 0f99e27491..9ad8da5783 100644
--- a/cli/tests/unit/write_file_test.ts
+++ b/cli/tests/unit/write_file_test.ts
@@ -1,5 +1,6 @@
 // Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
 import {
+  assert,
   assertEquals,
   assertRejects,
   assertThrows,
@@ -251,6 +252,7 @@ unitTest(
     try {
       await Deno.writeFile(filename, data, { signal: ac.signal });
     } catch (e) {
+      assert(e instanceof Error);
       assertEquals(e.name, "AbortError");
     }
     const stat = Deno.statSync(filename);
@@ -269,6 +271,7 @@ unitTest(
     try {
       await Deno.writeFile(filename, data, { signal: ac.signal });
     } catch (e) {
+      assert(e instanceof Error);
       assertEquals(e.name, "AbortError");
     }
     const stat = Deno.statSync(filename);