diff --git a/res/css/views/rooms/_RoomUpgradeWarningBar.scss b/res/css/views/rooms/_RoomUpgradeWarningBar.scss
index 82785b82d2..fe81d3801a 100644
--- a/res/css/views/rooms/_RoomUpgradeWarningBar.scss
+++ b/res/css/views/rooms/_RoomUpgradeWarningBar.scss
@@ -16,7 +16,7 @@ limitations under the License.
 
 .mx_RoomUpgradeWarningBar {
     text-align: center;
-    height: 176px;
+    height: 235px;
     background-color: $event-selected-color;
     align-items: center;
     flex-direction: column;
diff --git a/res/css/views/settings/tabs/_SettingsTab.scss b/res/css/views/settings/tabs/_SettingsTab.scss
index 7fd8bceb50..88735f99b2 100644
--- a/res/css/views/settings/tabs/_SettingsTab.scss
+++ b/res/css/views/settings/tabs/_SettingsTab.scss
@@ -14,6 +14,10 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+.mx_SettingsTab_warningText {
+    color: $warning-color;
+}
+
 .mx_SettingsTab_heading {
     font-size: 20px;
     font-weight: 600;
diff --git a/src/SlashCommands.js b/src/SlashCommands.js
index 711346c4a7..039ccb928f 100644
--- a/src/SlashCommands.js
+++ b/src/SlashCommands.js
@@ -28,6 +28,7 @@ import {MATRIXTO_URL_PATTERN} from "./linkify-matrix";
 import * as querystring from "querystring";
 import MultiInviter from './utils/MultiInviter';
 import { linkifyAndSanitizeHtml } from './HtmlUtils';
+import QuestionDialog from "./components/views/dialogs/QuestionDialog";
 
 class Command {
     constructor({name, args='', description, runFn, hideCompletionAfterSpace=false}) {
@@ -105,7 +106,72 @@ export const CommandMap = {
         description: _td('Upgrades a room to a new version'),
         runFn: function(roomId, args) {
             if (args) {
-                return success(MatrixClientPeg.get().upgradeRoom(roomId, args));
+                const room = MatrixClientPeg.get().getRoom(roomId);
+                Modal.createTrackedDialog('Slash Commands', 'upgrade room confirmation',
+                    QuestionDialog, {
+                    title: _t('Room upgrade confirmation'),
+                    description: (
+                        <div>
+                            <p>{_t("Upgrading a room can be destructive and isn't always necessary.")}</p>
+                            <p>
+                                {_t(
+                                    "Room upgrades are usually recommended when a room version is considered " +
+                                    "<i>unstable</i>. Unstable room versions might have bugs, missing features, or " +
+                                    "security vulnerabilities.",
+                                    {}, {
+                                        "i": (sub) => <i>{sub}</i>,
+                                    },
+                                )}
+                            </p>
+                            <p>
+                                {_t(
+                                    "Room upgrades usually only affect <i>server-side</i> processing of the " +
+                                    "room. If you're having problems with your Riot client, please file an issue " +
+                                    "with <issueLink />.",
+                                    {}, {
+                                        "i": (sub) => <i>{sub}</i>,
+                                        "issueLink": () => {
+                                            return <a href="https://github.com/vector-im/riot-web/issues/new/choose"
+                                                      target="_blank" rel="noopener">
+                                                https://github.com/vector-im/riot-web/issues/new/choose
+                                            </a>;
+                                        },
+                                    },
+                                )}
+                            </p>
+                            <p>
+                                {_t(
+                                    "<b>Warning</b>: Upgrading a room will <i>not automatically migrate room " +
+                                    "members to the new version of the room.</i> We'll post a link to the new room " +
+                                    "in the old version of the room - room members will have to click this link to " +
+                                    "join the new room.",
+                                    {}, {
+                                        "b": (sub) => <b>{sub}</b>,
+                                        "i": (sub) => <i>{sub}</i>,
+                                    },
+                                )}
+                            </p>
+                            <p>
+                                {_t(
+                                    "Please confirm that you'd like to go forward with upgrading this room " +
+                                    "from <oldVersion /> to <newVersion />",
+                                    {},
+                                    {
+                                        oldVersion: () => <code>{room ? room.getVersion() : "1"}</code>,
+                                        newVersion: () => <code>{args}</code>,
+                                    },
+                                )}
+                            </p>
+                        </div>
+                    ),
+                    button: _t("Upgrade"),
+                    onFinished: (confirm) => {
+                        if (!confirm) return;
+
+                        MatrixClientPeg.get().upgradeRoom(roomId, args);
+                    },
+                });
+                return success();
             }
             return reject(this.getUsage());
         },
diff --git a/src/components/views/rooms/RoomUpgradeWarningBar.js b/src/components/views/rooms/RoomUpgradeWarningBar.js
index 3a11f46e51..589608dcfa 100644
--- a/src/components/views/rooms/RoomUpgradeWarningBar.js
+++ b/src/components/views/rooms/RoomUpgradeWarningBar.js
@@ -37,41 +37,43 @@ module.exports = React.createClass({
     render: function() {
         const AccessibleButton = sdk.getComponent('elements.AccessibleButton');
 
-        let upgradeText = (
-            <div>
+        return (
+            <div className="mx_RoomUpgradeWarningBar">
+                <div className="mx_RoomUpgradeWarningBar_header">
+                    {_t(
+                        "This room is running room version <roomVersion />, which this homeserver has " +
+                        "marked as <i>unstable</i>.",
+                        {},
+                        {
+                            "roomVersion": () => <code>{this.props.room.getVersion()}</code>,
+                            "i": (sub) => <i>{sub}</i>,
+                        },
+                    )}
+                </div>
                 <div className="mx_RoomUpgradeWarningBar_body">
-                    {_t("This room is using an unstable room version. If you aren't expecting " +
-                        "this, please upgrade the room.")}
+                    <p>
+                        {_t(
+                            "Upgrading this room will shut down the current instance of the room and create " +
+                            "an upgraded room with the same name.",
+                        )}
+                    </p>
+                    <p>
+                        {_t(
+                            "<b>Warning</b>: Upgrading a room will <i>not automatically migrate room members " +
+                            "to the new version of the room.</i> We'll post a link to the new room in the old " +
+                            "version of the room - room members will have to click this link to join the new room.",
+                            {}, {
+                                "b": (sub) => <b>{sub}</b>,
+                                "i": (sub) => <i>{sub}</i>,
+                            },
+                        )}
+                    </p>
                 </div>
                 <p className="mx_RoomUpgradeWarningBar_upgradelink">
                     <AccessibleButton onClick={this.onUpgradeClick}>
-                        {_t("Click here to upgrade to the latest room version.")}
+                        {_t("Upgrade this room to the recommended room version")}
                     </AccessibleButton>
                 </p>
-            </div>
-        );
-        if (this.props.recommendation.urgent) {
-            upgradeText = (
-                <div>
-                    <div className="mx_RoomUpgradeWarningBar_header">
-                        {_t("There is a known vulnerability affecting this room.")}
-                    </div>
-                    <div className="mx_RoomUpgradeWarningBar_body">
-                        {_t("This room version is vulnerable to malicious modification of room state.")}
-                    </div>
-                    <p className="mx_RoomUpgradeWarningBar_upgradelink">
-                        <AccessibleButton onClick={this.onUpgradeClick}>
-                            {_t("Click here to upgrade to the latest room version and ensure room integrity " +
-                                "is protected.")}
-                        </AccessibleButton>
-                    </p>
-                </div>
-            );
-        }
-
-        return (
-            <div className="mx_RoomUpgradeWarningBar">
-                {upgradeText}
                 <div className="mx_RoomUpgradeWarningBar_small">
                     {_t("Only room administrators will see this warning")}
                 </div>
diff --git a/src/components/views/settings/tabs/room/AdvancedRoomSettingsTab.js b/src/components/views/settings/tabs/room/AdvancedRoomSettingsTab.js
index 3c6a7addc3..cabc196e40 100644
--- a/src/components/views/settings/tabs/room/AdvancedRoomSettingsTab.js
+++ b/src/components/views/settings/tabs/room/AdvancedRoomSettingsTab.js
@@ -67,9 +67,22 @@ export default class AdvancedRoomSettingsTab extends React.Component {
         let roomUpgradeButton;
         if (this.state.upgradeRecommendation && this.state.upgradeRecommendation.needsUpgrade) {
             roomUpgradeButton = (
-                <AccessibleButton onClick={this._upgradeRoom} kind='primary'>
-                    {_t("Upgrade room to version %(ver)s", {ver: this.state.upgradeRecommendation.version})}
-                </AccessibleButton>
+                <div>
+                    <p className='mx_SettingsTab_warningText'>
+                        {_t(
+                            "<b>Warning</b>: Upgrading a room will <i>not automatically migrate room members " +
+                            "to the new version of the room.</i> We'll post a link to the new room in the old " +
+                            "version of the room - room members will have to click this link to join the new room.",
+                            {}, {
+                                "b": (sub) => <b>{sub}</b>,
+                                "i": (sub) => <i>{sub}</i>,
+                            },
+                        )}
+                    </p>
+                    <AccessibleButton onClick={this._upgradeRoom} kind='primary'>
+                        {_t("Upgrade this room to the recommended room version")}
+                    </AccessibleButton>
+                </div>
             );
         }
 
diff --git a/src/i18n/strings/en_EN.json b/src/i18n/strings/en_EN.json
index e23be021e8..ef4bc75d27 100644
--- a/src/i18n/strings/en_EN.json
+++ b/src/i18n/strings/en_EN.json
@@ -132,6 +132,13 @@
     "/ddg is not a command": "/ddg is not a command",
     "To use it, just wait for autocomplete results to load and tab through them.": "To use it, just wait for autocomplete results to load and tab through them.",
     "Upgrades a room to a new version": "Upgrades a room to a new version",
+    "Room upgrade confirmation": "Room upgrade confirmation",
+    "Upgrading a room can be destructive and isn't always necessary.": "Upgrading a room can be destructive and isn't always necessary.",
+    "Room upgrades are usually recommended when a room version is considered <i>unstable</i>. Unstable room versions might have bugs, missing features, or security vulnerabilities.": "Room upgrades are usually recommended when a room version is considered <i>unstable</i>. Unstable room versions might have bugs, missing features, or security vulnerabilities.",
+    "Room upgrades usually only affect <i>server-side</i> processing of the room. If you're having problems with your Riot client, please file an issue with <issueLink />.": "Room upgrades usually only affect <i>server-side</i> processing of the room. If you're having problems with your Riot client, please file an issue with <issueLink />.",
+    "<b>Warning</b>: Upgrading a room will <i>not automatically migrate room members to the new version of the room.</i> We'll post a link to the new room in the old version of the room - room members will have to click this link to join the new room.": "<b>Warning</b>: Upgrading a room will <i>not automatically migrate room members to the new version of the room.</i> We'll post a link to the new room in the old version of the room - room members will have to click this link to join the new room.",
+    "Please confirm that you'd like to go forward with upgrading this room from <oldVersion /> to <newVersion />": "Please confirm that you'd like to go forward with upgrading this room from <oldVersion /> to <newVersion />",
+    "Upgrade": "Upgrade",
     "Changes your display nickname": "Changes your display nickname",
     "Changes your display nickname in the current room only": "Changes your display nickname in the current room only",
     "Changes colour scheme of current room": "Changes colour scheme of current room",
@@ -581,7 +588,7 @@
     "Camera": "Camera",
     "Voice & Video": "Voice & Video",
     "This room is not accessible by remote Matrix servers": "This room is not accessible by remote Matrix servers",
-    "Upgrade room to version %(ver)s": "Upgrade room to version %(ver)s",
+    "Upgrade this room to the recommended room version": "Upgrade this room to the recommended room version",
     "Room information": "Room information",
     "Internal room ID:": "Internal room ID:",
     "Room version": "Room version",
@@ -802,11 +809,8 @@
     "Not now": "Not now",
     "Don't ask me again": "Don't ask me again",
     "Add a topic": "Add a topic",
-    "This room is using an unstable room version. If you aren't expecting this, please upgrade the room.": "This room is using an unstable room version. If you aren't expecting this, please upgrade the room.",
-    "Click here to upgrade to the latest room version.": "Click here to upgrade to the latest room version.",
-    "There is a known vulnerability affecting this room.": "There is a known vulnerability affecting this room.",
-    "This room version is vulnerable to malicious modification of room state.": "This room version is vulnerable to malicious modification of room state.",
-    "Click here to upgrade to the latest room version and ensure room integrity is protected.": "Click here to upgrade to the latest room version and ensure room integrity is protected.",
+    "This room is running room version <roomVersion />, which this homeserver has marked as <i>unstable</i>.": "This room is running room version <roomVersion />, which this homeserver has marked as <i>unstable</i>.",
+    "Upgrading this room will shut down the current instance of the room and create an upgraded room with the same name.": "Upgrading this room will shut down the current instance of the room and create an upgraded room with the same name.",
     "Only room administrators will see this warning": "Only room administrators will see this warning",
     "This Room": "This Room",
     "All Rooms": "All Rooms",