diff --git a/frontend_tests/node_tests/hotkey.js b/frontend_tests/node_tests/hotkey.js
index 499752bcb1..8768baf23d 100644
--- a/frontend_tests/node_tests/hotkey.js
+++ b/frontend_tests/node_tests/hotkey.js
@@ -174,13 +174,13 @@ run_test("basic_chars", () => {
         };
         try {
             return hotkey.process_keypress(e);
-        } catch (err) {
+        } catch (error) {
             // An exception will be thrown here if a different
             // function is called than the one declared.  Try to
             // provide a useful error message.
             // add a newline to separate from other console output.
             console.log('\nERROR: Mapping for character "' + e.which + '" does not match tests.');
-            throw err;
+            throw error;
         }
     }
 
@@ -384,13 +384,13 @@ run_test("motion_keys", () => {
 
         try {
             return hotkey.process_keydown(e);
-        } catch (err) {
+        } catch (error) {
             // An exception will be thrown here if a different
             // function is called than the one declared.  Try to
             // provide a useful error message.
             // add a newline to separate from other console output.
             console.log('\nERROR: Mapping for character "' + e.which + '" does not match tests.');
-            throw err;
+            throw error;
         }
     }
 
diff --git a/frontend_tests/node_tests/util.js b/frontend_tests/node_tests/util.js
index 2337a97cbd..89e6a2527d 100644
--- a/frontend_tests/node_tests/util.js
+++ b/frontend_tests/node_tests/util.js
@@ -111,8 +111,8 @@ run_test("robust_uri_decode", () => {
     });
     try {
         util.robust_uri_decode("%E0%A4%A");
-    } catch (e) {
-        assert.equal(e, "foo");
+    } catch (error) {
+        assert.equal(error, "foo");
     }
 });
 
diff --git a/frontend_tests/puppeteer_lib/common.js b/frontend_tests/puppeteer_lib/common.js
index 16458c7422..c834e57df2 100644
--- a/frontend_tests/puppeteer_lib/common.js
+++ b/frontend_tests/puppeteer_lib/common.js
@@ -460,8 +460,8 @@ class CommonUtils {
         const page = await this.get_page();
         try {
             await test_function(page);
-        } catch (e) {
-            console.log(e);
+        } catch (error) {
+            console.log(error);
 
             // Take a screenshot, and increment the screenshot_id.
             await this.screenshot(page, `failure-${this.screenshot_id}`);
diff --git a/frontend_tests/zjsunit/index.js b/frontend_tests/zjsunit/index.js
index a5e432f0a5..662730b75a 100644
--- a/frontend_tests/zjsunit/index.js
+++ b/frontend_tests/zjsunit/index.js
@@ -143,11 +143,11 @@ try {
         namespace.restore();
         Handlebars.HandlebarsEnvironment();
     });
-} catch (e) {
-    if (e.stack) {
-        console.info(short_tb(e.stack));
+} catch (error) {
+    if (error.stack) {
+        console.info(short_tb(error.stack));
     } else {
-        console.info(e);
+        console.info(error);
     }
     process.exit(1);
 }
diff --git a/static/js/channel.js b/static/js/channel.js
index f6bd828d44..c263422fa8 100644
--- a/static/js/channel.js
+++ b/static/js/channel.js
@@ -55,11 +55,11 @@ function call(args, idempotent) {
                         save_compose: true,
                     });
                 }
-            } catch (ex) {
+            } catch (error) {
                 blueslip.error(
                     "Unexpected 403 response from server",
                     {xhr: xhr.responseText, args},
-                    ex.stack,
+                    error.stack,
                 );
             }
         }
diff --git a/static/js/markdown.js b/static/js/markdown.js
index 945c3e97e5..0a78eef99d 100644
--- a/static/js/markdown.js
+++ b/static/js/markdown.js
@@ -401,12 +401,12 @@ function handleRealmFilter(pattern, matches) {
 function handleTex(tex, fullmatch) {
     try {
         return katex.renderToString(tex);
-    } catch (ex) {
-        if (ex.message.startsWith("KaTeX parse error")) {
+    } catch (error) {
+        if (error.message.startsWith("KaTeX parse error")) {
             // TeX syntax error
             return '<span class="tex-error">' + _.escape(fullmatch) + "</span>";
         }
-        blueslip.error(ex);
+        blueslip.error(error);
         return undefined;
     }
 }
@@ -460,11 +460,11 @@ function python_to_js_filter(pattern, url) {
     let final_regex = null;
     try {
         final_regex = new RegExp(pattern, js_flags);
-    } catch (ex) {
+    } catch (error) {
         // We have an error computing the generated regex syntax.
         // We'll ignore this realm filter for now, but log this
         // failure for debugging later.
-        blueslip.error("python_to_js_filter: " + ex.message);
+        blueslip.error("python_to_js_filter: " + error.message);
     }
     return [final_regex, url];
 }
diff --git a/static/js/reload.js b/static/js/reload.js
index fa0408d417..1ba7cccbdc 100644
--- a/static/js/reload.js
+++ b/static/js/reload.js
@@ -141,10 +141,10 @@ exports.initialize = function () {
             if (send_now) {
                 compose.finish();
             }
-        } catch (err) {
+        } catch (error) {
             // We log an error if we can't open the compose box, but otherwise
             // we continue, since this is not critical.
-            blueslip.warn(err.toString());
+            blueslip.warn(error.toString());
         }
     }
 
@@ -181,8 +181,8 @@ function do_reload_app(send_after_reload, save_pointer, save_narrow, save_compos
     if (save_pointer || save_narrow || save_compose) {
         try {
             preserve_state(send_after_reload, save_pointer, save_narrow, save_compose);
-        } catch (ex) {
-            blueslip.error("Failed to preserve state", undefined, ex.stack);
+        } catch (error) {
+            blueslip.error("Failed to preserve state", undefined, error.stack);
         }
     }
 
@@ -212,8 +212,8 @@ function do_reload_app(send_after_reload, save_pointer, save_narrow, save_compos
 
     try {
         server_events.cleanup_event_queue();
-    } catch (ex) {
-        blueslip.error("Failed to cleanup before reloading", undefined, ex.stack);
+    } catch (error) {
+        blueslip.error("Failed to cleanup before reloading", undefined, error.stack);
     }
 
     window.location.reload(true);
diff --git a/static/js/server_events.js b/static/js/server_events.js
index 523d3a6a66..d7b00c4f92 100644
--- a/static/js/server_events.js
+++ b/static/js/server_events.js
@@ -31,8 +31,12 @@ function get_events_success(events) {
     for (const event of events) {
         try {
             get_events_params.last_event_id = Math.max(get_events_params.last_event_id, event.id);
-        } catch (ex) {
-            blueslip.error("Failed to update last_event_id", {event: clean_event(event)}, ex.stack);
+        } catch (error) {
+            blueslip.error(
+                "Failed to update last_event_id",
+                {event: clean_event(event)},
+                error.stack,
+            );
         }
     }
 
@@ -81,11 +85,11 @@ function get_events_success(events) {
     for (const event of events) {
         try {
             dispatch_event(event);
-        } catch (ex1) {
+        } catch (error) {
             blueslip.error(
-                "Failed to process an event\n" + blueslip.exception_msg(ex1),
+                "Failed to process an event\n" + blueslip.exception_msg(error),
                 {event: clean_event(event)},
-                ex1.stack,
+                error.stack,
             );
         }
     }
@@ -113,11 +117,11 @@ function get_events_success(events) {
 
                 message_events.insert_new_messages(messages, sent_by_this_client);
             }
-        } catch (ex2) {
+        } catch (error) {
             blueslip.error(
-                "Failed to insert new messages\n" + blueslip.exception_msg(ex2),
+                "Failed to insert new messages\n" + blueslip.exception_msg(error),
                 undefined,
-                ex2.stack,
+                error.stack,
             );
         }
     }
@@ -129,11 +133,11 @@ function get_events_success(events) {
     if (update_message_events.length !== 0) {
         try {
             message_events.update_messages(update_message_events);
-        } catch (ex3) {
+        } catch (error) {
             blueslip.error(
-                "Failed to update messages\n" + blueslip.exception_msg(ex3),
+                "Failed to update messages\n" + blueslip.exception_msg(error),
                 undefined,
-                ex3.stack,
+                error.stack,
             );
         }
     }
@@ -208,11 +212,11 @@ function get_events(options) {
                 hide_ui_connection_error();
 
                 get_events_success(data.events);
-            } catch (ex) {
+            } catch (error) {
                 blueslip.error(
-                    "Failed to handle get_events success\n" + blueslip.exception_msg(ex),
+                    "Failed to handle get_events success\n" + blueslip.exception_msg(error),
                     undefined,
-                    ex.stack,
+                    error.stack,
                 );
             }
             get_events_timeout = setTimeout(get_events, 0);
@@ -251,11 +255,11 @@ function get_events(options) {
                 } else {
                     hide_ui_connection_error();
                 }
-            } catch (ex) {
+            } catch (error) {
                 blueslip.error(
-                    "Failed to handle get_events error\n" + blueslip.exception_msg(ex),
+                    "Failed to handle get_events error\n" + blueslip.exception_msg(error),
                     undefined,
-                    ex.stack,
+                    error.stack,
                 );
             }
             const retry_sec = Math.min(90, Math.exp(get_events_failures / 2));
diff --git a/static/js/submessage.js b/static/js/submessage.js
index 9a40832435..1cef93d8ed 100644
--- a/static/js/submessage.js
+++ b/static/js/submessage.js
@@ -28,8 +28,8 @@ exports.process_submessages = function (in_opts) {
     // damage that may be triggered by one rogue message.
     try {
         return exports.do_process_submessages(in_opts);
-    } catch (err) {
-        blueslip.error("in process_submessages: " + err.message);
+    } catch (error) {
+        blueslip.error("in process_submessages: " + error.message);
         return undefined;
     }
 };
diff --git a/static/js/util.js b/static/js/util.js
index ec4ceb9171..29818ab12e 100644
--- a/static/js/util.js
+++ b/static/js/util.js
@@ -125,9 +125,9 @@ exports.robust_uri_decode = function (str) {
     while (end > 0) {
         try {
             return decodeURIComponent(str.slice(0, end));
-        } catch (e) {
-            if (!(e instanceof URIError)) {
-                throw e;
+        } catch (error) {
+            if (!(error instanceof URIError)) {
+                throw error;
             }
             end -= 1;
         }
diff --git a/tools/message-screenshot.js b/tools/message-screenshot.js
index 63fba2dd6b..db05cff026 100644
--- a/tools/message-screenshot.js
+++ b/tools/message-screenshot.js
@@ -70,8 +70,8 @@ async function run() {
         const imageDir = path.dirname(imagePath);
         mkdirp.sync(imageDir);
         await page.screenshot({path: imagePath, clip});
-    } catch (e) {
-        console.log(e);
+    } catch (error) {
+        console.log(error);
         process.exit(1);
     } finally {
         await browser.close();