diff --git a/web/src/compose_recipient.js b/web/src/compose_recipient.js
index 1b0ccdf790..65b08da84a 100644
--- a/web/src/compose_recipient.js
+++ b/web/src/compose_recipient.js
@@ -120,7 +120,7 @@ export function get_posting_policy_error_message() {
 export function check_posting_policy_for_compose_box() {
     const banner_text = get_posting_policy_error_message();
     if (banner_text === "") {
-        $(".message-send-controls").removeClass("disabled-message-send-controls");
+        compose_validate.set_recipient_disallowed(false);
         compose_banner.clear_errors();
         return;
     }
@@ -129,7 +129,7 @@ export function check_posting_policy_for_compose_box() {
     if (compose_state.selected_recipient_id === "direct") {
         banner_classname = compose_banner.CLASSNAMES.private_messages_disabled;
     }
-    $(".message-send-controls").addClass("disabled-message-send-controls");
+    compose_validate.set_recipient_disallowed(true);
     compose_banner.show_error_message(banner_text, banner_classname, $("#compose_banners"));
 }
 
diff --git a/web/src/compose_tooltips.js b/web/src/compose_tooltips.js
index 66ad143bb4..67697e5bde 100644
--- a/web/src/compose_tooltips.js
+++ b/web/src/compose_tooltips.js
@@ -6,6 +6,7 @@ import render_narrow_to_compose_recipients_tooltip from "../templates/narrow_to_
 
 import * as compose_recipient from "./compose_recipient";
 import * as compose_state from "./compose_state";
+import * as compose_validate from "./compose_validate";
 import {$t} from "./i18n";
 import * as narrow_state from "./narrow_state";
 import * as popover_menus from "./popover_menus";
@@ -133,7 +134,9 @@ export function initialize() {
         // in the new design
         target: [".disabled-message-send-controls"],
         maxWidth: 350,
-        content: () => compose_recipient.get_posting_policy_error_message(),
+        content: () =>
+            compose_recipient.get_posting_policy_error_message() ||
+            compose_validate.get_disabled_send_tooltip(),
         appendTo: () => document.body,
         onHidden(instance) {
             instance.destroy();
diff --git a/web/src/compose_validate.js b/web/src/compose_validate.js
index bb47e30dc1..5929b218f5 100644
--- a/web/src/compose_validate.js
+++ b/web/src/compose_validate.js
@@ -23,9 +23,43 @@ import * as sub_store from "./sub_store";
 import * as util from "./util";
 
 let user_acknowledged_wildcard = false;
+let upload_in_progress = false;
+let message_too_long = false;
+let recipient_disallowed = false;
 
 export let wildcard_mention_large_stream_threshold = 15;
 
+export function set_upload_in_progress(status) {
+    upload_in_progress = status;
+    update_send_button_status();
+}
+
+function set_message_too_long(status) {
+    message_too_long = status;
+    update_send_button_status();
+}
+
+export function set_recipient_disallowed(status) {
+    recipient_disallowed = status;
+    update_send_button_status();
+}
+
+function update_send_button_status() {
+    $(".message-send-controls").toggleClass(
+        "disabled-message-send-controls",
+        message_too_long || upload_in_progress || recipient_disallowed,
+    );
+}
+
+export function get_disabled_send_tooltip() {
+    if (message_too_long) {
+        return $t({defaultMessage: "Message length shouldn't be greater than 10000 characters."});
+    } else if (upload_in_progress) {
+        return $t({defaultMessage: "Cannot send message while files are being uploaded."});
+    }
+    return "";
+}
+
 export function needs_subscribe_warning(user_id, stream_id) {
     // This returns true if all of these conditions are met:
     //  * the user is valid
@@ -655,7 +689,7 @@ export function check_overflow_text() {
             compose_banner.CLASSNAMES.message_too_long,
             $("#compose_banners"),
         );
-        $("#compose-send-button").prop("disabled", true);
+        set_message_too_long(true);
     } else if (text.length > 0.9 * max_length) {
         $indicator.removeClass("over_limit");
         $("textarea#compose-textarea").removeClass("over_limit");
@@ -665,13 +699,13 @@ export function check_overflow_text() {
                 max_length,
             }),
         );
-        $("#compose-send-button").prop("disabled", false);
+        set_message_too_long(false);
         $(`#compose_banners .${CSS.escape(compose_banner.CLASSNAMES.message_too_long)}`).remove();
     } else {
         $indicator.text("");
         $("textarea#compose-textarea").removeClass("over_limit");
 
-        $("#compose-send-button").prop("disabled", false);
+        set_message_too_long(false);
         $(`#compose_banners .${CSS.escape(compose_banner.CLASSNAMES.message_too_long)}`).remove();
     }
 
diff --git a/web/src/upload.js b/web/src/upload.js
index 863f8210bc..37c4a6558e 100644
--- a/web/src/upload.js
+++ b/web/src/upload.js
@@ -9,6 +9,7 @@ import * as compose_banner from "./compose_banner";
 import * as compose_reply from "./compose_reply";
 import * as compose_state from "./compose_state";
 import * as compose_ui from "./compose_ui";
+import * as compose_validate from "./compose_validate";
 import {csrf_token} from "./csrf";
 import {$t} from "./i18n";
 import * as message_lists from "./message_lists";
@@ -129,7 +130,11 @@ export function get_item(key, config, file_id) {
 export function hide_upload_banner(uppy, config, file_id) {
     get_item("upload_banner", config, file_id).remove();
     if (uppy.getFiles().length === 0) {
-        get_item("send_button", config).prop("disabled", false);
+        if (config.mode === "compose") {
+            compose_validate.set_upload_in_progress(false);
+        } else {
+            get_item("send_button", config).prop("disabled", false);
+        }
     }
 }
 
@@ -157,7 +162,6 @@ export function show_error_message(
     message = $t({defaultMessage: "An unknown error occurred."}),
     file_id = null,
 ) {
-    get_item("send_button", config).prop("disabled", false);
     if (file_id) {
         $(`${get_item("upload_banner_identifier", config, file_id)} .moving_bar`).hide();
         get_item("upload_banner", config, file_id).removeClass("info").addClass("error");
@@ -195,8 +199,6 @@ export async function upload_files(uppy, config, files) {
         get_item("markdown_preview_hide_button", config).trigger("click");
     }
 
-    get_item("send_button", config).prop("disabled", true);
-
     for (const file of files) {
         try {
             compose_ui.insert_syntax_and_focus(
@@ -217,6 +219,11 @@ export async function upload_files(uppy, config, files) {
             continue;
         }
 
+        if (config.mode === "compose") {
+            compose_validate.set_upload_in_progress(true);
+        } else {
+            get_item("send_button", config).prop("disabled", true);
+        }
         add_upload_banner(
             config,
             "info",
@@ -405,16 +412,16 @@ export function setup_upload(config) {
     });
 
     uppy.on("upload-error", (file, _error, response) => {
+        // The files with failed upload should be removed since uppy doesn't allow files in the store
+        // to be re-uploaded again.
+        uppy.removeFile(file.id);
+
         const message = response ? response.body.msg : undefined;
         // Hide the upload status banner on error so only the error banner shows
         hide_upload_banner(uppy, config, file.id);
         show_error_message(config, message, file.id);
         compose_ui.replace_syntax(get_translated_status(file), "", get_item("textarea", config));
         compose_ui.autosize_textarea(get_item("textarea", config));
-
-        // The files with failed upload should be removed since uppy doesn't allow files in the store
-        // to be re-uploaded again.
-        uppy.removeFile(file.id);
     });
 
     uppy.on("restriction-failed", (file) => {
diff --git a/web/tests/compose_validate.test.js b/web/tests/compose_validate.test.js
index e8d0b595a3..906ed1880f 100644
--- a/web/tests/compose_validate.test.js
+++ b/web/tests/compose_validate.test.js
@@ -561,7 +561,6 @@ test_ui("test_check_overflow_text", ({mock_template}) => {
 
     const $textarea = $("textarea#compose-textarea");
     const $indicator = $("#compose-limit-indicator");
-    const $send_button = $("#compose-send-button");
     let banner_rendered = false;
     mock_template("compose_banner/compose_banner.hbs", false, (data) => {
         assert.equal(data.classname, compose_banner.CLASSNAMES.message_too_long);
@@ -585,7 +584,7 @@ test_ui("test_check_overflow_text", ({mock_template}) => {
     assert.equal(limit_indicator_html, "10001​/10000\n");
     assert.ok($textarea.hasClass("over_limit"));
     assert.ok(banner_rendered);
-    assert.ok($send_button.prop("disabled"));
+    assert.ok($(".message-send-controls").hasClass("disabled-message-send-controls"));
 
     // Indicator should show orange colored text
     banner_rendered = false;
@@ -594,7 +593,7 @@ test_ui("test_check_overflow_text", ({mock_template}) => {
     assert.ok(!$indicator.hasClass("over_limit"));
     assert.equal(limit_indicator_html, "9001​/10000\n");
     assert.ok(!$textarea.hasClass("over_limit"));
-    assert.ok(!$send_button.prop("disabled"));
+    assert.ok(!$(".message-send-controls").hasClass("disabled-message-send-controls"));
     assert.ok(!banner_rendered);
 
     // Indicator must be empty
diff --git a/web/tests/upload.test.js b/web/tests/upload.test.js
index a3b6374fb8..b30be12880 100644
--- a/web/tests/upload.test.js
+++ b/web/tests/upload.test.js
@@ -194,7 +194,7 @@ test("show_error_message", ({mock_template}) => {
     $("#compose-send-button").prop("disabled", true);
 
     upload.show_error_message({mode: "compose"}, "Error message");
-    assert.equal($("#compose-send-button").prop("disabled"), false);
+    assert.ok(!$(".message-send-controls").hasClass("disabled-message-send-controls"));
     assert.ok(banner_shown);
 
     mock_template("compose_banner/upload_banner.hbs", false, (data) => {
@@ -237,9 +237,9 @@ test("upload_files", async ({mock_template, override_rewire}) => {
         assert.equal(config.mode, "compose");
     });
     const config = {mode: "compose"};
-    $("#compose-send-button").prop("disabled", false);
+    $(".message-send-controls").removeClass("disabled-message-send-controls");
     await upload.upload_files(uppy, config, []);
-    assert.ok(!$("#compose-send-button").prop("disabled"));
+    assert.ok(!$(".message-send-controls").hasClass("disabled-message-send-controls"));
 
     let banner_shown = false;
     mock_template("compose_banner/upload_banner.hbs", false, (data) => {
@@ -277,7 +277,7 @@ test("upload_files", async ({mock_template, override_rewire}) => {
     $("#compose .undo_markdown_preview").on("click", () => {
         markdown_preview_hide_button_clicked = true;
     });
-    $("#compose-send-button").prop("disabled", false);
+    $(".message-send-controls").removeClass("disabled-message-send-controls");
     $("#compose_banners .upload_banner").remove();
     $("#compose .undo_markdown_preview").show();
 
@@ -286,7 +286,7 @@ test("upload_files", async ({mock_template, override_rewire}) => {
         banner_shown = true;
     });
     await upload.upload_files(uppy, config, files);
-    assert.ok($("#compose-send-button").prop("disabled"));
+    assert.ok($(".message-send-controls").hasClass("disabled-message-send-controls"));
     assert.ok(banner_shown);
     assert.ok(compose_ui_insert_syntax_and_focus_called);
     assert.ok(compose_ui_autosize_textarea_called);