diff --git a/gomuks b/gomuks
index a59201a..9e6254b 160000
--- a/gomuks
+++ b/gomuks
@@ -1 +1 @@
-Subproject commit a59201a03b0f3e14e0ecf1ce2c964e6f1115ad4f
+Subproject commit 9e6254b703a841d1e9ee64dbaf90d5a1b798696e
diff --git a/lib/controllers/capabilities.dart b/lib/controllers/capabilities.dart
new file mode 100644
index 0000000..3b7a76f
--- /dev/null
+++ b/lib/controllers/capabilities.dart
@@ -0,0 +1,14 @@
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:nexus/controllers/client.dart";
+import "package:nexus/models/capabilities.dart";
+
+class CapabilitiesController extends AsyncNotifier<Capabilities> {
+  @override
+  Future<Capabilities> build() =>
+      ref.read(ClientController.provider.notifier).getCapabilities();
+
+  static final provider =
+      AsyncNotifierProvider<CapabilitiesController, Capabilities>(
+        CapabilitiesController.new,
+      );
+}
diff --git a/lib/controllers/client.dart b/lib/controllers/client.dart
index 766fe1e..361b4e6 100644
--- a/lib/controllers/client.dart
+++ b/lib/controllers/client.dart
@@ -488,11 +488,21 @@ class ClientController(final String? accountId) extends AsyncNotifier<int> {
       }))["visibility"] ==
       "public";
 
-  Future<void> setRoomPublished(String roomId, bool published) =>
-      _sendCommand("publish_room", {
-        "room_id": roomId,
-        "visibility": published ? "public" : "private",
-      });
+  Future<void> setRoomPublished(String roomId, bool published) => _sendCommand(
+    "publish_room",
+    {"room_id": roomId, "visibility": published ? "public" : "private"},
+  );
+
+  Future<String> upgradeRoom(
+    String roomId,
+    String version, {
+    ISet<String> additionalCreators = const .empty(),
+  }) async => (await _sendCommand("upgrade_room", {
+    "room_id": roomId,
+    "new_version": version,
+    if (additionalCreators.isNotEmpty)
+      "additional_creators": additionalCreators.toList(),
+  }))["replacement_room"];
 
   /// The room [alias] points to, or null if it doesn't exist.
   Future<String?> resolveAlias(String alias) async {
diff --git a/lib/controllers/room_power_levels.dart b/lib/controllers/room_power_levels.dart
index e33c436..7001eec 100644
--- a/lib/controllers/room_power_levels.dart
+++ b/lib/controllers/room_power_levels.dart
@@ -1,6 +1,7 @@
 import "package:fast_immutable_collections/fast_immutable_collections.dart";
 import "package:flutter_riverpod/flutter_riverpod.dart";
 import "package:nexus/controllers/rooms.dart";
+import "package:nexus/helpers/extensions/room_version_at_least.dart";
 import "package:nexus/models/content/content.dart";
 import "package:nexus/models/content/create.dart";
 import "package:nexus/models/content/power_levels.dart";
@@ -26,8 +27,7 @@ class RoomPowerLevelsController(final String roomId)
       _ => null,
     };
     // Creators only outrank everyone from room version 12, earlier ones just have a power level
-    final creatorsPrivileged =
-        (int.tryParse(create?.roomVersion ?? "") ?? 0) >= 12;
+    final creatorsPrivileged = (create?.roomVersion).versionAtLeast(12);
 
     return .new(
       content: switch (stateEvent(.powerLevels)?.content) {
diff --git a/lib/controllers/room_settings_sections.dart b/lib/controllers/room_settings_sections.dart
index 7136e05..bf7159a 100644
--- a/lib/controllers/room_settings_sections.dart
+++ b/lib/controllers/room_settings_sections.dart
@@ -14,6 +14,7 @@ import "package:nexus/controllers/room_published.dart";
 import "package:nexus/controllers/rooms.dart";
 import "package:nexus/controllers/space_edges.dart";
 import "package:nexus/helpers/extensions/join_rule_name.dart";
+import "package:nexus/helpers/extensions/room_version_at_least.dart";
 import "package:nexus/helpers/file_dialog_helper.dart";
 import "package:nexus/helpers/hooks/saving.dart";
 import "package:nexus/main.dart";
@@ -29,6 +30,7 @@ import "package:nexus/models/content/membership.dart";
 import "package:nexus/models/content/message.dart";
 import "package:nexus/models/content/name.dart";
 import "package:nexus/models/content/power_levels.dart";
+import "package:nexus/models/content/tombstone.dart";
 import "package:nexus/models/content/topic.dart";
 import "package:nexus/models/join_rule.dart";
 import "package:nexus/models/power_level_permission.dart";
@@ -46,6 +48,7 @@ import "package:nexus/widgets/settings/local_aliases_sheet.dart";
 import "package:nexus/widgets/settings/power_level_entry_sheet.dart";
 import "package:nexus/widgets/settings/power_level_tile.dart";
 import "package:nexus/widgets/settings/text_setting_tile.dart";
+import "package:nexus/widgets/settings/upgrade_room_sheet.dart";
 
 class RoomSettingsSectionsController(final String roomId)
     extends AsyncNotifier<IMap<String, IList<SettingsCategory>>> {
@@ -122,18 +125,18 @@ class RoomSettingsSectionsController(final String roomId)
       ?canonicalAlias.alias,
     ]).toISet();
 
-    final roomVersion = switch (stateContent(.create)) {
-      CreateContent(:final roomVersion) => int.tryParse(roomVersion),
+    final versionName = switch (stateContent(.create)) {
+      CreateContent(:final roomVersion) => roomVersion,
       _ => null,
     };
-    bool versionAtLeast(int version) =>
-        roomVersion == null || roomVersion >= version;
+    final canUpgrade =
+        canSet(.tombstone) && stateContent(.tombstone) is! TombstoneContent;
     final joinRuleOptions = [
       JoinRule.public,
       JoinRule.invite,
-      if (versionAtLeast(7)) JoinRule.knock,
-      if (versionAtLeast(8)) JoinRule.restricted,
-      if (versionAtLeast(10)) JoinRule.knockRestricted,
+      if (versionName.versionAtLeast(7)) JoinRule.knock,
+      if (versionName.versionAtLeast(8)) JoinRule.restricted,
+      if (versionName.versionAtLeast(10)) JoinRule.knockRestricted,
     ];
     bool isRestricted(JoinRule rule) =>
         rule == .restricted || rule == .knockRestricted;
@@ -577,9 +580,8 @@ class RoomSettingsSectionsController(final String roomId)
                         ? (value) => saving.run(
                             () => ref
                                 .read(
-                                  RoomPublishedController.provider(
-                                    roomId,
-                                  ).notifier,
+                                  RoomPublishedController.provider(roomId)
+                                      .notifier,
                                 )
                                 .set(value)
                                 .onError(showError),
@@ -589,6 +591,52 @@ class RoomSettingsSectionsController(final String roomId)
                 },
               ),
             ),
+            .new(
+              title: "Room Version",
+              description: "The rules the room follows, set when it's created.",
+              icon: Icons.upgrade,
+              builder: (title, description, icon) => HookBuilder(
+                builder: (context) {
+                  final saving = Saving.use();
+
+                  return ListTile(
+                    leading: Icon(icon),
+                    title: Text(title),
+                    subtitle: Text(
+                      versionName == null
+                          ? description
+                          : "Version $versionName",
+                    ),
+                    trailing: TextButton(
+                      onPressed:
+                          canUpgrade && versionName != null && !saving.active
+                          ? () => context.showAdaptiveSheet(
+                              (_) => UpgradeRoomSheet(
+                                roomId: roomId,
+                                currentVersion: versionName,
+                                creators: roomPowerLevels.creators.remove(
+                                  userId ?? "",
+                                ),
+                                userId: userId,
+                                onSave: (version, creators) => saving.run(
+                                  () => client
+                                      .upgradeRoom(
+                                        roomId,
+                                        version,
+                                        additionalCreators: creators,
+                                      )
+                                      .then<void>((_) {})
+                                      .onError(showError),
+                                ),
+                              ),
+                            )
+                          : null,
+                      child: Text("Upgrade"),
+                    ),
+                  );
+                },
+              ),
+            ),
           ]),
         ),
         .new(
diff --git a/lib/controllers/unified_push.dart b/lib/controllers/unified_push.dart
index 01635d9..25675e2 100644
--- a/lib/controllers/unified_push.dart
+++ b/lib/controllers/unified_push.dart
@@ -8,6 +8,7 @@ import "package:flutter_riverpod/flutter_riverpod.dart";
 import "package:intl/intl.dart";
 import "package:nexus/controllers/accounts.dart";
 import "package:nexus/controllers/active_account.dart";
+import "package:nexus/controllers/capabilities.dart";
 import "package:nexus/controllers/selected_room.dart";
 import "package:nexus/controllers/notification.dart";
 import "package:nexus/controllers/client_state.dart";
@@ -215,9 +216,9 @@ class UnifiedPushController extends AsyncNotifier<String?> {
     state = .loading();
     try {
       await Future(() async {
-        final capabilities = await ref
-            .read(ClientController.provider.notifier)
-            .getCapabilities();
+        final capabilities = await ref.read(
+          CapabilitiesController.provider.future,
+        );
 
         if (capabilities.webpush?.vapid == null) {
           throw UnsupportedError(
diff --git a/lib/controllers/unified_push_allowed.dart b/lib/controllers/unified_push_allowed.dart
index 03ce3b0..6dd1cf7 100644
--- a/lib/controllers/unified_push_allowed.dart
+++ b/lib/controllers/unified_push_allowed.dart
@@ -1,7 +1,7 @@
 import "dart:io";
 
 import "package:flutter_riverpod/flutter_riverpod.dart";
-import "package:nexus/controllers/client.dart";
+import "package:nexus/controllers/capabilities.dart";
 import "package:nexus/controllers/unified_push_distributors.dart";
 
 class UnifiedPushAllowedController extends AsyncNotifier<String?> {
@@ -19,9 +19,9 @@ class UnifiedPushAllowedController extends AsyncNotifier<String?> {
           : "Your platform is not currently supported by UnifiedPush"}.";
     }
 
-    final capabilities = await ref
-        .read(ClientController.provider.notifier)
-        .getCapabilities();
+    final capabilities = await ref.watch(
+      CapabilitiesController.provider.future,
+    );
 
     if (capabilities.webpush?.vapid == null) {
       return "Your homeserver does not support MSC4174 (Web Push), and therefore cannot send notifications to Nexus.";
diff --git a/lib/helpers/extensions/room_version_at_least.dart b/lib/helpers/extensions/room_version_at_least.dart
new file mode 100644
index 0000000..f66d573
--- /dev/null
+++ b/lib/helpers/extensions/room_version_at_least.dart
@@ -0,0 +1,8 @@
+extension RoomVersionAtLeast on String? {
+  /// Whether this room version is [version] or newer. Unknown ones, like
+  /// unstable versions, are assumed to be new enough.
+  bool versionAtLeast(int version) => switch (int.tryParse(this ?? "")) {
+    final number? => number >= version,
+    null => true,
+  };
+}
diff --git a/lib/models/capabilities.dart b/lib/models/capabilities.dart
index 6830170..cdf86b7 100644
--- a/lib/models/capabilities.dart
+++ b/lib/models/capabilities.dart
@@ -1,3 +1,4 @@
+import "package:fast_immutable_collections/fast_immutable_collections.dart";
 import "package:freezed_annotation/freezed_annotation.dart";
 
 part "capabilities.freezed.dart";
@@ -7,6 +8,7 @@ part "capabilities.g.dart";
 @JsonSerializable()
 class const Capabilities({
   @JsonKey(name: "org.matrix.msc4174.webpush") final WebPush? webpush,
+  @JsonKey(name: "m.room_versions") final RoomVersions? roomVersions,
 }) with _$Capabilities {
   Map<String, Object?> toJson() => _$CapabilitiesToJson(this);
 
@@ -23,3 +25,30 @@ class const WebPush({required final bool enabled, final String? vapid})
   factory WebPush.fromJson(Map<String, Object?> json) =>
       _$WebPushFromJson(json);
 }
+
+@Freezed(toJson: false, fromJson: false)
+@JsonSerializable()
+class const RoomVersions({
+  @JsonKey(name: "default") required final String defaultVersion,
+  @JsonKey(fromJson: RoomVersionStability.mapFromJson)
+  required final IMap<String, RoomVersionStability> available,
+}) with _$RoomVersions {
+  Map<String, Object?> toJson() => _$RoomVersionsToJson(this);
+
+  factory RoomVersions.fromJson(Map<String, Object?> json) =>
+      _$RoomVersionsFromJson(json);
+}
+
+enum RoomVersionStability {
+  stable,
+  unstable,
+  unknown;
+
+  static IMap<String, RoomVersionStability> mapFromJson(
+    Map<String, dynamic> json,
+  ) => IMap.fromJson(
+    json,
+    (version) => version as String,
+    (stability) => values.asNameMap()[stability] ?? unknown,
+  );
+}
diff --git a/lib/widgets/settings/add_users_power_level_sheet.dart b/lib/widgets/settings/add_users_power_level_sheet.dart
index ec865f4..b406414 100644
--- a/lib/widgets/settings/add_users_power_level_sheet.dart
+++ b/lib/widgets/settings/add_users_power_level_sheet.dart
@@ -1,15 +1,9 @@
-import "package:collection/collection.dart";
 import "package:fast_immutable_collections/fast_immutable_collections.dart";
 import "package:flutter_hooks/flutter_hooks.dart";
-import "package:hooks_riverpod/hooks_riverpod.dart";
 import "package:material_ui/material_ui.dart";
 import "package:material_adaptive_sheets/material_adaptive_sheets.dart";
-import "package:nexus/controllers/members.dart";
-import "package:nexus/helpers/extensions/get_localpart.dart";
-import "package:nexus/models/content/membership.dart";
-import "package:nexus/widgets/avatar_or_hash.dart";
+import "package:nexus/widgets/settings/member_chooser.dart";
 import "package:nexus/widgets/settings/power_level_field.dart";
-import "package:nexus/widgets/settings/search_chooser.dart";
 
 /// Chooses users of [roomId] to give a power level of their own.
 class const AddUsersPowerLevelSheet({
@@ -22,43 +16,16 @@ class const AddUsersPowerLevelSheet({
   required final double ownLevel,
   required final void Function(ISet<String> users, int level) onSave,
   super.key,
-}) extends HookConsumerWidget {
+}) extends HookWidget {
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
+  Widget build(BuildContext context) {
     final chosen = useState(const ISet<String>.empty());
-    final error = useState<String?>(null);
-    final searchController = useTextEditingController();
     final levelController = useTextEditingController(text: "0");
     final level = PowerLevelField.levelFrom(
       useValueListenable(levelController).text,
       ownLevel,
     );
 
-    final members = IMap.fromEntries(
-      (ref.watch(MembersController.provider(roomId)).value ??
-              const ISet.empty())
-          .map(
-            (event) => switch ((event.stateKey, event.content)) {
-              (final userId?, final MembershipContent content)
-                  when content.status == .join || content.status == .invite =>
-                MapEntry(userId, content),
-              _ => null,
-            },
-          )
-          .nonNulls,
-    );
-
-    String nameOf(String id) => members[id]?.displayName ?? id.localpart;
-
-    void add(String id) {
-      if (existing.contains(id)) {
-        error.value = "Already has a power level";
-        return;
-      }
-      chosen.value = chosen.value.add(id);
-      searchController.clear();
-    }
-
     final valid = chosen.value.isNotEmpty && level != null;
     void save() {
       Navigator.of(context).pop();
@@ -72,33 +39,15 @@ class const AddUsersPowerLevelSheet({
         TextButton(onPressed: valid ? save : null, child: Text("Save")),
       ],
       children: [
-        SearchChooser(
-          controller: searchController,
+        MemberChooser(
+          roomId: roomId,
           chosen: chosen.value,
-          options: members.keys
-              .where((id) => !existing.contains(id))
-              .sortedBy((id) => nameOf(id).toLowerCase())
-              .toIList(),
-          nameOf: nameOf,
-          avatarOf: (id) =>
-              AvatarOrHash(members[id]?.avatarUrl, nameOf(id), dimension: 40),
-          subtitleOf: (id) => id,
-          onAdded: add,
+          excluded: existing,
+          excludedError: "Already has a power level",
+          onAdded: (id) => chosen.value = chosen.value.add(id),
           onRemoved: (id) => chosen.value = chosen.value.remove(id),
-          onSubmitted: (text, topMatch) {
-            if (RegExp(r"^@[^:]+:.+$").hasMatch(text)) {
-              add(text);
-            } else if (topMatch != null) {
-              add(topMatch);
-            } else {
-              error.value = "Enter a user ID";
-            }
-          },
-          onChanged: (_) => error.value = null,
           label: "Add user",
-          hint: "Search members, or enter a user ID",
           removeTooltip: "Remove user",
-          error: error.value,
           autofocus: true,
         ),
         PowerLevelField(
diff --git a/lib/widgets/settings/member_chooser.dart b/lib/widgets/settings/member_chooser.dart
new file mode 100644
index 0000000..18ed2e2
--- /dev/null
+++ b/lib/widgets/settings/member_chooser.dart
@@ -0,0 +1,91 @@
+import "package:collection/collection.dart";
+import "package:fast_immutable_collections/fast_immutable_collections.dart";
+import "package:flutter_hooks/flutter_hooks.dart";
+import "package:hooks_riverpod/hooks_riverpod.dart";
+import "package:material_ui/material_ui.dart";
+import "package:nexus/controllers/members.dart";
+import "package:nexus/helpers/extensions/get_localpart.dart";
+import "package:nexus/models/content/membership.dart";
+import "package:nexus/widgets/avatar_or_hash.dart";
+import "package:nexus/widgets/settings/search_chooser.dart";
+
+/// The [chosen] users, above a field searching [roomId]'s members, or taking a user ID, to choose more.
+class const MemberChooser({
+  required final String roomId,
+  required final ISet<String> chosen,
+  required final void Function(String userId) onAdded,
+  required final void Function(String userId) onRemoved,
+  required final String label,
+  required final String removeTooltip,
+
+  /// Users who can't be chosen, so aren't suggested.
+  final ISet<String> excluded = const .empty(),
+
+  /// Shown when trying to choose one of the [excluded] users.
+  final String excludedError = "Can't be chosen",
+  final String? emptyText,
+  final bool autofocus = false,
+  super.key,
+}) extends HookConsumerWidget {
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final error = useState<String?>(null);
+    final searchController = useTextEditingController();
+
+    final members = IMap.fromEntries(
+      (ref.watch(MembersController.provider(roomId)).value ??
+              const ISet.empty())
+          .map(
+            (event) => switch ((event.stateKey, event.content)) {
+              (final userId?, final MembershipContent content)
+                  when content.status == .join || content.status == .invite =>
+                MapEntry(userId, content),
+              _ => null,
+            },
+          )
+          .nonNulls,
+    );
+
+    String nameOf(String id) => members[id]?.displayName ?? id.localpart;
+
+    void add(String id) {
+      if (excluded.contains(id)) {
+        error.value = excludedError;
+        return;
+      }
+      onAdded(id);
+      searchController.clear();
+    }
+
+    return SearchChooser(
+      controller: searchController,
+      chosen: chosen,
+      options: members.keys
+          .where((id) => !excluded.contains(id))
+          .sortedBy((id) => nameOf(id).toLowerCase())
+          .toIList(),
+      nameOf: nameOf,
+      avatarOf: (id) =>
+          AvatarOrHash(members[id]?.avatarUrl, nameOf(id), dimension: 40),
+      subtitleOf: (id) => id,
+      onAdded: add,
+      onRemoved: onRemoved,
+      onSubmitted: (text, topMatch) {
+        if (RegExp(r"^@[^:]+:.+$").hasMatch(text)) {
+          add(text);
+        } else if (topMatch != null) {
+          add(topMatch);
+        } else {
+          error.value = "Enter a user ID";
+        }
+      },
+      onChanged: (_) => error.value = null,
+      label: label,
+      hint: "Search members, or enter a user ID",
+      removeTooltip: removeTooltip,
+      emptyText: emptyText,
+      error: error.value,
+      autofocus: autofocus,
+    );
+  }
+}
diff --git a/lib/widgets/settings/upgrade_room_sheet.dart b/lib/widgets/settings/upgrade_room_sheet.dart
new file mode 100644
index 0000000..a54325b
--- /dev/null
+++ b/lib/widgets/settings/upgrade_room_sheet.dart
@@ -0,0 +1,100 @@
+import "package:collection/collection.dart";
+import "package:fast_immutable_collections/fast_immutable_collections.dart";
+import "package:flutter_hooks/flutter_hooks.dart";
+import "package:hooks_riverpod/hooks_riverpod.dart";
+import "package:material_ui/material_ui.dart";
+import "package:material_adaptive_sheets/material_adaptive_sheets.dart";
+import "package:nexus/controllers/capabilities.dart";
+import "package:nexus/helpers/extensions/better_when.dart";
+import "package:nexus/helpers/extensions/room_version_at_least.dart";
+import "package:nexus/widgets/settings/dialog_list_tile.dart";
+import "package:nexus/widgets/settings/member_chooser.dart";
+
+/// Chooses a room version to upgrade [roomId] to, and its additional creators if the version has them.
+class const UpgradeRoomSheet({
+  required final String roomId,
+  required final String currentVersion,
+
+  /// The room's current creators, other than the user, to keep in the new room.
+  required final ISet<String> creators,
+  required final String? userId,
+  required final void Function(String version, ISet<String> creators) onSave,
+  super.key,
+}) extends HookConsumerWidget {
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final roomVersions = ref
+        .watch(CapabilitiesController.provider)
+        .whenData((capabilities) => capabilities.roomVersions);
+    final chosen = useState<String?>(null);
+    final chosenCreators = useState(creators);
+
+    final versions = roomVersions.value;
+    final version = chosen.value ?? versions?.defaultVersion;
+
+    final valid = version != null;
+    final withCreators = valid && version.versionAtLeast(12);
+    void save() {
+      Navigator.of(context).pop();
+      onSave(version!, withCreators ? chosenCreators.value : const .empty());
+    }
+
+    return SheetLayout(
+      title: Text("Upgrade Room"),
+      actions: [
+        TextButton(onPressed: Navigator.of(context).pop, child: Text("Cancel")),
+        TextButton(onPressed: valid ? save : null, child: Text("Upgrade")),
+      ],
+      children: [
+        Text(
+          "Upgrading creates a new room with the chosen version and closes this one, pointing its members to the new room. Members will have to join the new room themselves.",
+        ),
+        roomVersions.betterWhen(
+          data: (versions) => versions == null
+              ? Text(
+                  "Your homeserver didn't list the room versions it supports.",
+                )
+              : DialogListTile<String>(
+                  icon: Icon(Icons.upgrade),
+                  title: "Room Version",
+                  subtitle: Text("The version the new room will have."),
+                  value: version,
+                  options: versions.available.keys.sortedBy(
+                    (option) => int.tryParse(option) ?? double.infinity,
+                  ),
+                  getName: (option) => switch ([
+                    if (option == currentVersion) "current",
+                    if (option == versions.defaultVersion) "default",
+                    if (versions.available[option] == .unstable) "unstable",
+                  ]) {
+                    final labels when labels.isNotEmpty =>
+                      "$option (${labels.join(", ")})",
+                    _ => option,
+                  },
+                  onChanged: (value) => chosen.value = value,
+                ),
+        ),
+        AnimatedSize(
+          duration: Durations.medium2,
+          curve: Curves.easeInOut,
+          alignment: .topCenter,
+          child: withCreators
+              ? MemberChooser(
+                  roomId: roomId,
+                  chosen: chosenCreators.value,
+                  excluded: ISet([?userId]),
+                  excludedError: "You'll be a creator already",
+                  onAdded: (id) =>
+                      chosenCreators.value = chosenCreators.value.add(id),
+                  onRemoved: (id) =>
+                      chosenCreators.value = chosenCreators.value.remove(id),
+                  label: "Add creator",
+                  removeTooltip: "Remove creator",
+                  emptyText: "Creators outrank everyone in the new room, and can't be demoted. You'll be one, and can add others.",
+                )
+              : const SizedBox(width: .infinity),
+        ),
+      ],
+    );
+  }
+}