diff --git a/devtools/client/debugger/src/client/firefox/targets.js b/devtools/client/debugger/src/client/firefox/targets.js
index fd6835aed29f..70afc5ac786f 100644
--- a/devtools/client/debugger/src/client/firefox/targets.js
+++ b/devtools/client/debugger/src/client/firefox/targets.js
@@ -48,7 +48,7 @@ async function attachTargets(targetLists, args) {
       // But workers targets are still only managed by the debugger codebase
       // and so we have to attach their thread actor
       if (!threadFront) {
-        [, threadFront] = await targetFront.attachThread({
+        threadFront = await targetFront.attachThread({
           ...defaultThreadOptions(),
           ...args.options,
         });
diff --git a/devtools/client/debugger/test/mochitest/browser_dbg-chrome-debugging.js b/devtools/client/debugger/test/mochitest/browser_dbg-chrome-debugging.js
index 2c931342262e..3fb56643c97b 100644
--- a/devtools/client/debugger/test/mochitest/browser_dbg-chrome-debugging.js
+++ b/devtools/client/debugger/test/mochitest/browser_dbg-chrome-debugging.js
@@ -55,7 +55,7 @@ add_task(async function() {
   const descriptorFront = await gClient.mainRoot.getMainProcess();
   const front = await descriptorFront.getTarget();
   await front.attach();
-  const [, threadFront] = await front.attachThread();
+  const threadFront = await front.attachThread();
   gThreadFront = threadFront;
   gBrowser.selectedTab = BrowserTestUtils.addTab(gBrowser, "about:mozilla");
 
diff --git a/devtools/client/framework/test/browser_target_server_compartment.js b/devtools/client/framework/test/browser_target_server_compartment.js
index 8da193e8b1d6..829918ef6db0 100644
--- a/devtools/client/framework/test/browser_target_server_compartment.js
+++ b/devtools/client/framework/test/browser_target_server_compartment.js
@@ -39,7 +39,7 @@ async function testChromeTab() {
   const target = await TargetFactory.forTab(tab);
   await target.attach();
 
-  const [, threadFront] = await target.attachThread();
+  const threadFront = await target.attachThread();
   await threadFront.resume();
 
   const { sources } = await threadFront.getSources();
@@ -108,7 +108,7 @@ async function testMainProcess() {
   const target = await targetDescriptor.getTarget();
   await target.attach();
 
-  const [, threadFront] = await target.attachThread();
+  const threadFront = await target.attachThread();
   await threadFront.resume();
   const { sources } = await threadFront.getSources();
   ok(
diff --git a/devtools/client/framework/toolbox.js b/devtools/client/framework/toolbox.js
index 4287a4b87534..03279409a5b7 100644
--- a/devtools/client/framework/toolbox.js
+++ b/devtools/client/framework/toolbox.js
@@ -729,7 +729,7 @@ Toolbox.prototype = {
 
   _attachAndResumeThread: async function(target) {
     const options = defaultThreadOptions();
-    const [, threadFront] = await target.attachThread(options);
+    const threadFront = await target.attachThread(options);
 
     try {
       await threadFront.resume();
diff --git a/devtools/client/shared/test/browser_dbg_debugger-statement.js b/devtools/client/shared/test/browser_dbg_debugger-statement.js
index 49f5fcb69915..0750310e0bb3 100644
--- a/devtools/client/shared/test/browser_dbg_debugger-statement.js
+++ b/devtools/client/shared/test/browser_dbg_debugger-statement.js
@@ -44,7 +44,7 @@ async function testEarlyDebuggerStatement(client, tab, targetFront) {
   client.off("paused", onPaused);
 
   // Now attach and resume...
-  const [, threadFront] = await targetFront.attachThread();
+  const threadFront = await targetFront.attachThread();
   await threadFront.resume();
   ok(true, "Pause wasn't called before we've attached.");
 
diff --git a/devtools/client/shared/test/helper_workers.js b/devtools/client/shared/test/helper_workers.js
index f55c17954915..b7b774fe6529 100644
--- a/devtools/client/shared/test/helper_workers.js
+++ b/devtools/client/shared/test/helper_workers.js
@@ -265,7 +265,7 @@ this.removeTab = function removeTab(tab, win) {
 async function attachThreadActorForTab(tab) {
   const target = await TargetFactory.forTab(tab);
   await target.attach();
-  const [, threadFront] = await target.attachThread();
+  const threadFront = await target.attachThread();
   await threadFront.resume();
   return { client: target.client, threadFront };
 }
diff --git a/devtools/docs/backend/client-api.md b/devtools/docs/backend/client-api.md
index f0140fce0347..896cea0e51d5 100644
--- a/devtools/docs/backend/client-api.md
+++ b/devtools/docs/backend/client-api.md
@@ -113,7 +113,7 @@ Once the application is attached to a tab, it can attach to its thread in order
 // Assuming the application is already attached to the tab, and response is the first
 // argument of the attachTarget callback.
 
-client.attachThread(response.threadActor).then(function([response, threadFront]) {
+client.attachThread(response.threadActor).then(function(threadFront) {
   if (!threadFront) {
     return;
   }
@@ -178,7 +178,7 @@ function debugTab() {
     // Attach to the tab.
     targetFront.attach().then(() => {
       // Attach to the thread (context).
-      targetFront.attachThread().then(([response, threadFront]) => {
+      targetFront.attachThread().then((threadFront) => {
         // Attach listeners for thread events.
         threadFront.on("paused", onPause);
         threadFront.on("resumed", fooListener);
diff --git a/devtools/server/tests/chrome/test_webextension-addon-debugging-connect.html b/devtools/server/tests/chrome/test_webextension-addon-debugging-connect.html
index f1952cf0adcf..c691771ef7c0 100644
--- a/devtools/server/tests/chrome/test_webextension-addon-debugging-connect.html
+++ b/devtools/server/tests/chrome/test_webextension-addon-debugging-connect.html
@@ -53,7 +53,7 @@ add_task(async function test_webextension_addon_debugging_connect() {
 
   // When running in oop mode we can explicitly attach the thread without locking
   // the main process.
-  const [, threadFront] = await addonTarget.attachThread();
+  const threadFront = await addonTarget.attachThread();
 
   ok(threadFront, "Got a threadFront for the target addon");
   is(threadFront.paused, true, "The addon threadActor is paused");
diff --git a/devtools/server/tests/xpcshell/head_dbg.js b/devtools/server/tests/xpcshell/head_dbg.js
index 43675c3d7bb8..15be1a619aec 100644
--- a/devtools/server/tests/xpcshell/head_dbg.js
+++ b/devtools/server/tests/xpcshell/head_dbg.js
@@ -791,7 +791,7 @@ async function setupTestFromUrl(url) {
   const targetFront = findTab(tabs, "test");
   await targetFront.attach();
 
-  const [, threadFront] = await attachThread(targetFront);
+  const threadFront = await attachThread(targetFront);
   await resume(threadFront);
 
   const sourceUrl = getFileUrl(url);
diff --git a/devtools/server/tests/xpcshell/test_reattach-thread.js b/devtools/server/tests/xpcshell/test_reattach-thread.js
index e6abdc676fbc..f6340e47341b 100644
--- a/devtools/server/tests/xpcshell/test_reattach-thread.js
+++ b/devtools/server/tests/xpcshell/test_reattach-thread.js
@@ -11,7 +11,7 @@ add_task(
   threadFrontTest(async ({ threadFront, debuggee, client, targetFront }) => {
     await threadFront.detach();
     Assert.equal(threadFront.state, "detached");
-    const [, newThreadFront] = await targetFront.attachThread({});
+    const newThreadFront = await targetFront.attachThread({});
     Assert.notEqual(threadFront, newThreadFront);
     Assert.equal(newThreadFront.state, "paused");
     Assert.equal(targetFront.threadFront, newThreadFront);
diff --git a/devtools/server/tests/xpcshell/test_xpcshell_debugging.js b/devtools/server/tests/xpcshell/test_xpcshell_debugging.js
index a3fdc41d65b0..b48e92ea824c 100644
--- a/devtools/server/tests/xpcshell/test_xpcshell_debugging.js
+++ b/devtools/server/tests/xpcshell/test_xpcshell_debugging.js
@@ -38,7 +38,7 @@ add_task(async function() {
   // Even though we have no tabs, getMainProcess gives us the chrome debugger.
   const targetDescriptor = await client.mainRoot.getMainProcess();
   const front = await targetDescriptor.getTarget();
-  const [, threadFront] = await front.attachThread();
+  const threadFront = await front.attachThread();
 
   // tell the thread to do the initial resume. This would cause the
   // xpcshell test harness to resume and load the file under test.
diff --git a/devtools/shared/fronts/targets/target-mixin.js b/devtools/shared/fronts/targets/target-mixin.js
index 6eb0e30a12ba..d2a5d3bf36d9 100644
--- a/devtools/shared/fronts/targets/target-mixin.js
+++ b/devtools/shared/fronts/targets/target-mixin.js
@@ -361,7 +361,7 @@ function TargetMixin(parentClass) {
         );
       }
       this.threadFront = await this.getFront("thread");
-      const result = await this.threadFront.attach(options);
+      await this.threadFront.attach(options);
 
       this.threadFront.on("newSource", this._onNewSource);
 
@@ -369,7 +369,7 @@ function TargetMixin(parentClass) {
       // wait for the thread to be attached can resume.
       this._resolveOnThreadAttached();
 
-      return [result, this.threadFront];
+      return this.threadFront;
     }
 
     // Listener for "newSource" event fired by the thread actor
diff --git a/devtools/shared/webconsole/test/chrome/common.js b/devtools/shared/webconsole/test/chrome/common.js
index 9a85d2a5323f..582aa40e28b6 100644
--- a/devtools/shared/webconsole/test/chrome/common.js
+++ b/devtools/shared/webconsole/test/chrome/common.js
@@ -83,7 +83,7 @@ var _attachConsole = async function(listeners, attachToTab, attachToWorker) {
 
     // Attach the Target and the target thread in order to instantiate the console client.
     await target.attach();
-    const [, threadFront] = await target.attachThread();
+    const threadFront = await target.attachThread();
     await threadFront.resume();
 
     const webConsoleFront = await target.getFront("console");