diff --git a/Buildscripts/TactilitySDK/Tools/update-sdk.py b/Buildscripts/TactilitySDK/Tools/update-sdk.py
index e32c1c868..b21830e94 100755
--- a/Buildscripts/TactilitySDK/Tools/update-sdk.py
+++ b/Buildscripts/TactilitySDK/Tools/update-sdk.py
@@ -52,36 +52,59 @@ def read_installed_tools_hash(version_directory):
         return None
 
 
-def extract(archive_data, target_directory):
-    """Extracts next to target_directory and then replaces it, refusing entries outside of it"""
-    staging_directory = f"{target_directory}.new"
-    shutil.rmtree(staging_directory, ignore_errors=True)
-    os.makedirs(staging_directory)
-    root = os.path.realpath(staging_directory)
-    try:
-        with zipfile.ZipFile(io.BytesIO(archive_data)) as archive:
-            for member in archive.infolist():
-                destination = os.path.realpath(os.path.join(root, member.filename))
-                if not destination.startswith(root + os.sep):
-                    fail(f"invalid entry in the archive: {member.filename}")
-            archive.extractall(root)
-    except zipfile.BadZipFile:
+class Update:
+    """Stages every component next to its installed folder, so a failed download leaves the installation untouched"""
+
+    def __init__(self):
+        # (target directory, staging directory, metadata path, metadata)
+        self.staged = []
+
+    def stage(self, archive_data, target_directory, metadata_path, metadata):
+        """Extracts into a staging folder, refusing entries outside of it"""
+        staging_directory = f"{target_directory}.new"
         shutil.rmtree(staging_directory, ignore_errors=True)
-        fail("the downloaded archive is invalid")
-    shutil.rmtree(target_directory, ignore_errors=True)
-    os.replace(staging_directory, target_directory)
+        os.makedirs(staging_directory)
+        self.staged.append((target_directory, staging_directory, metadata_path, metadata))
+        root = os.path.realpath(staging_directory)
+        try:
+            with zipfile.ZipFile(io.BytesIO(archive_data)) as archive:
+                for member in archive.infolist():
+                    destination = os.path.realpath(os.path.join(root, member.filename))
+                    if not destination.startswith(root + os.sep):
+                        fail(f"invalid entry in the archive: {member.filename}")
+                archive.extractall(root)
+        except zipfile.BadZipFile:
+            fail("the downloaded archive is invalid")
 
+    def discard(self):
+        for _, staging_directory, _, _ in self.staged:
+            shutil.rmtree(staging_directory, ignore_errors=True)
+        self.staged = []
 
-def install_platform(platform_directory, archive_data, commit):
-    extract(archive_data, os.path.join(platform_directory, "TactilitySDK"))
-    with open(os.path.join(platform_directory, "commit"), "w") as file:
-        file.write(commit)
-
-
-def install_tools(version_directory, archive_data, sha256):
-    extract(archive_data, os.path.join(version_directory, "tools"))
-    with open(os.path.join(version_directory, "tools.sha256"), "w") as file:
-        file.write(sha256)
+    def commit(self):
+        """Replaces the installed folders, and puts the previous ones back when that fails"""
+        replaced = []
+        try:
+            for target_directory, staging_directory, _, _ in self.staged:
+                backup_directory = f"{target_directory}.old"
+                shutil.rmtree(backup_directory, ignore_errors=True)
+                if os.path.isdir(target_directory):
+                    os.replace(target_directory, backup_directory)
+                replaced.append((target_directory, backup_directory))
+                os.replace(staging_directory, target_directory)
+        except OSError as error:
+            for target_directory, backup_directory in reversed(replaced):
+                shutil.rmtree(target_directory, ignore_errors=True)
+                if os.path.isdir(backup_directory):
+                    os.replace(backup_directory, target_directory)
+            self.discard()
+            fail(f"failed to install the update: {error}")
+        for _, _, metadata_path, metadata in self.staged:
+            with open(metadata_path, "w") as file:
+                file.write(metadata)
+        for _, backup_directory in replaced:
+            shutil.rmtree(backup_directory, ignore_errors=True)
+        self.staged = []
 
 
 def main():
@@ -99,22 +122,28 @@ def main():
         fail("the downloaded index.json is invalid")
     commit = index.get("gitCommit", "")
     available = index.get("platforms", {})
-    updated = False
-    tools = index.get("tools")
-    if tools is not None and read_installed_tools_hash(version_directory) != tools.get("sha256"):
-        print(f"Updating the tools of SDK {version}")
-        archive_data = fetch(f"{CDN_URL}/sdk/{version}/{tools['file']}")
-        if hashlib.sha256(archive_data).hexdigest() != tools["sha256"]:
-            fail("the downloaded tools don't match their checksum")
-        install_tools(version_directory, archive_data, tools["sha256"])
-        updated = True
-    for platform in installed_platforms(version_directory):
-        platform_directory = os.path.join(version_directory, f"platform-{platform}")
-        if read_commit(platform_directory) == commit or platform not in available:
-            continue
-        print(f"Updating SDK {version} for {platform}")
-        install_platform(platform_directory, fetch(f"{CDN_URL}/sdk/{version}/{available[platform]}"), commit)
-        updated = True
+    update = Update()
+    try:
+        tools = index.get("tools")
+        if tools is not None and read_installed_tools_hash(version_directory) != tools.get("sha256"):
+            print(f"Downloading the tools of SDK {version}", flush=True)
+            archive_data = fetch(f"{CDN_URL}/sdk/{version}/{tools['file']}")
+            if hashlib.sha256(archive_data).hexdigest() != tools["sha256"]:
+                fail("the downloaded tools don't match their checksum")
+            update.stage(archive_data, os.path.join(version_directory, "tools"), os.path.join(version_directory, "tools.sha256"), tools["sha256"])
+        for platform in installed_platforms(version_directory):
+            platform_directory = os.path.join(version_directory, f"platform-{platform}")
+            if read_commit(platform_directory) == commit or platform not in available:
+                continue
+            print(f"Downloading SDK {version} for {platform}", flush=True)
+            archive_data = fetch(f"{CDN_URL}/sdk/{version}/{available[platform]}")
+            update.stage(archive_data, os.path.join(platform_directory, "TactilitySDK"), os.path.join(platform_directory, "commit"), commit)
+    except SystemExit:
+        update.discard()
+        print(f"SDK {version} was not changed", file=sys.stderr)
+        raise
+    updated = len(update.staged) > 0
+    update.commit()
     with open(os.path.join(version_directory, "index.json"), "wb") as file:
         file.write(index_data)
     print(f"SDK {version} was updated" if updated else f"SDK {version} is up to date")
diff --git a/Buildscripts/check-tt-version.py b/Buildscripts/check-tt-version.py
index 233d3385b..b30e4cf05 100755
--- a/Buildscripts/check-tt-version.py
+++ b/Buildscripts/check-tt-version.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-"""Fails when the files of tt changed since a base revision, but TT_VERSION in tt.py wasn't increased.
+"""Fails when the files of tt or its packaging changed since a base revision, but TT_VERSION in tt.py wasn't increased.
 Usage: check-tt-version.py <base revision>, e.g. origin/main"""
 
 import importlib.util
@@ -10,6 +10,8 @@ import sys
 
 ROOT_PATH = os.path.normpath(os.path.join(os.path.dirname(os.path.abspath(__file__)), ".."))
 VERSION_PATTERN = re.compile(r'^TT_VERSION = "([^"]+)"', re.MULTILINE)
+# Changes to what tt.zip contains, e.g. an added or removed file
+PACKAGING_FILE_NAME = "Buildscripts/release-tt.py"
 
 
 def load_file_names():
@@ -39,7 +41,7 @@ def main():
         sys.exit(2)
     base = sys.argv[1]
     file_names = load_file_names()
-    diff = git("diff", "--name-only", f"{base}...HEAD", "--", *file_names)
+    diff = git("diff", "--name-only", f"{base}...HEAD", "--", *file_names, PACKAGING_FILE_NAME)
     if diff.returncode != 0:
         print(f"git diff failed: {diff.stderr.strip()}", file=sys.stderr)
         sys.exit(2)
diff --git a/Documentation/ideas.md b/Documentation/ideas.md
index a3efcc896..ee5280a25 100644
--- a/Documentation/ideas.md
+++ b/Documentation/ideas.md
@@ -7,7 +7,6 @@
 
 ## Higher Priority
 
-- Remove screenshot app and replace with tt.py + screenshot.py: "tt screenshot [filepath]". if filepath isn't specified, save as screenshot-[yyyy-mm-dd].png
 - BlueTooth as radio backend for MeshCore/Meshtastic?
 - ESP-NOW as radio backend. Use it for MeshCore/Meshtastic?
 - Find out why the first build of an app with a clean build cache folder always fails
diff --git a/Modules/app-hub-module/source/app_hub_command.cpp b/Modules/app-hub-module/source/app_hub_command.cpp
index 6b516a87a..41470eb1b 100644
--- a/Modules/app-hub-module/source/app_hub_command.cpp
+++ b/Modules/app-hub-module/source/app_hub_command.cpp
@@ -40,6 +40,7 @@ static int report_error(const char* action, error_t error) {
 /**
  * Queues an operation and waits for its result.
  * The subscription is made before queueing, so the operation can't finish unnoticed.
+ * It times out after OPERATION_TIMEOUT without events of the operation, so a long update of many apps doesn't.
  * @param[in] finished_type the event that ends the operation and carries its result
  * @param[in] on_event called for the other events of the operation (optional)
  */
@@ -62,7 +63,7 @@ static error_t run_and_wait(
     error = operation(id, &operation_id);
     if (error == ERROR_NONE) {
         error = ERROR_TIMEOUT;
-        const TickType_t start = get_ticks();
+        TickType_t start = get_ticks();
         TickType_t elapsed = 0;
         bool finished = false;
         while (!finished && elapsed < OPERATION_TIMEOUT) {
@@ -72,6 +73,7 @@ static error_t run_and_wait(
                     if (event.operation_id != operation_id) {
                         continue;
                     }
+                    start = get_ticks();
                     if (event.type == finished_type) {
                         error = event.result;
                         finished = true;
diff --git a/Modules/http-module/private/http/private/http_parsing.h b/Modules/http-module/private/http/private/http_parsing.h
index 5e279561f..c0165ce21 100644
--- a/Modules/http-module/private/http/private/http_parsing.h
+++ b/Modules/http-module/private/http/private/http_parsing.h
@@ -20,5 +20,8 @@ bool http_parse_status_line(const std::string& line, int& statusCode);
 /** Parses a header line such as "Content-Length: 42". The name is returned in lower case, the value without surrounding whitespace. */
 bool http_parse_header_line(const std::string& line, std::string& name, std::string& value);
 
+/** Parses a Content-Length value: decimal digits only, without sign or overflow */
+bool http_parse_content_length(const std::string& value, long& length);
+
 /** Parses the size line of a chunk in a chunked body, e.g. "1a2b" or "1a2b;name=value" */
 bool http_parse_chunk_size(const std::string& line, size_t& size);
diff --git a/Modules/http-module/source/download_posix.cpp b/Modules/http-module/source/download_posix.cpp
index aa4db8603..6f5654ff1 100644
--- a/Modules/http-module/source/download_posix.cpp
+++ b/Modules/http-module/source/download_posix.cpp
@@ -299,6 +299,8 @@ HttpDownloadEvent http_download_run(const std::string& url, const std::string& c
 
     // -1 means the length is unknown: the body is chunked or ends when the server closes the connection
     long contentLength = -1;
+    std::string contentLengthValue;
+    bool hasContentLength = false;
     bool chunked = false;
     while (true) {
         if (!connection.readLine(line)) {
@@ -313,7 +315,8 @@ HttpDownloadEvent http_download_run(const std::string& url, const std::string& c
             continue;
         }
         if (name == "content-length") {
-            contentLength = strtol(value.c_str(), nullptr, 10);
+            contentLengthValue = value;
+            hasContentLength = true;
         } else if (name == "transfer-encoding" && value.find("chunked") != std::string::npos) {
             chunked = true;
         }
@@ -322,6 +325,10 @@ HttpDownloadEvent http_download_run(const std::string& url, const std::string& c
     if (statusCode < 200 || statusCode >= 300) {
         return http_download_make_error_event("Server response is not OK", statusCode);
     }
+    // A chunked body ignores the Content-Length
+    if (hasContentLength && !chunked && !http_parse_content_length(contentLengthValue, contentLength)) {
+        return http_download_make_error_event("Invalid Content-Length", statusCode);
+    }
     if (http_download_is_cancelled(link)) {
         return http_download_make_cancelled_event(statusCode);
     }
diff --git a/Modules/http-module/source/http_parsing.cpp b/Modules/http-module/source/http_parsing.cpp
index 61d4730b6..f783b4bb1 100644
--- a/Modules/http-module/source/http_parsing.cpp
+++ b/Modules/http-module/source/http_parsing.cpp
@@ -2,6 +2,7 @@
 #include <http/private/http_parsing.h>
 
 #include <cctype>
+#include <climits>
 #include <cstdlib>
 #include <string_view>
 
@@ -110,6 +111,22 @@ bool http_parse_header_line(const std::string& line, std::string& name, std::str
     return !name.empty();
 }
 
+bool http_parse_content_length(const std::string& value, long& length) {
+    if (value.empty() || value.find_first_not_of("0123456789") != std::string::npos) {
+        return false;
+    }
+    long result = 0;
+    for (const char c : value) {
+        const long digit = c - '0';
+        if (result > (LONG_MAX - digit) / 10) {
+            return false;
+        }
+        result = result * 10 + digit;
+    }
+    length = result;
+    return true;
+}
+
 bool http_parse_chunk_size(const std::string& line, size_t& size) {
     const std::string digits = trim(line.substr(0, line.find(';')));
     if (digits.empty() || digits.size() > sizeof(size_t) * 2) {
diff --git a/Modules/http-module/tests/source/http_parsing_test.cpp b/Modules/http-module/tests/source/http_parsing_test.cpp
index de9ac5227..b04b282a6 100644
--- a/Modules/http-module/tests/source/http_parsing_test.cpp
+++ b/Modules/http-module/tests/source/http_parsing_test.cpp
@@ -46,6 +46,21 @@ TEST_CASE("http_parse_header_line lowercases the name and trims the value") {
     CHECK_FALSE(http_parse_header_line(": empty name", name, value));
 }
 
+TEST_CASE("http_parse_content_length accepts decimal digits only") {
+    long length = -1;
+    REQUIRE(http_parse_content_length("42", length));
+    CHECK_EQ(length, 42);
+    REQUIRE(http_parse_content_length("0", length));
+    CHECK_EQ(length, 0);
+    CHECK_FALSE(http_parse_content_length("", length));
+    CHECK_FALSE(http_parse_content_length("-5", length));
+    CHECK_FALSE(http_parse_content_length("+5", length));
+    CHECK_FALSE(http_parse_content_length("12abc", length));
+    CHECK_FALSE(http_parse_content_length("1 2", length));
+    CHECK_FALSE(http_parse_content_length("99999999999999999999999", length));
+    CHECK_EQ(length, 0);
+}
+
 TEST_CASE("http_parse_chunk_size reads hexadecimal sizes and ignores extensions") {
     size_t size = 0;
     REQUIRE(http_parse_chunk_size("1a2B", size));
diff --git a/Tactility/Private/Tactility/app/timezone/TimeZoneView.h b/Tactility/Private/Tactility/app/timezone/TimeZoneView.h
index 6ab14d764..ff664a134 100644
--- a/Tactility/Private/Tactility/app/timezone/TimeZoneView.h
+++ b/Tactility/Private/Tactility/app/timezone/TimeZoneView.h
@@ -27,7 +27,7 @@ public:
 
     explicit TimeZoneView(OnSelected onSelected);
 
-    /** Waits for a running detection, which can take a few seconds. Destroy it without holding the LVGL lock. */
+    /** Cancels a running detection and waits for its lookup to end, which can take a few seconds */
     ~TimeZoneView();
 
     TimeZoneView(const TimeZoneView&) = delete;
@@ -59,6 +59,8 @@ private:
     std::unique_ptr<Timer> filterTimer;
     std::unique_ptr<Thread> detectThread;
     std::atomic<bool> detecting = false;
+    // Set when the view is destroyed, so a running detection ends without using it
+    std::atomic<bool> cancelled = false;
 
     // Valid while the widgets exist, guarded by the LVGL lock
     lv_obj_t* textarea = nullptr;
diff --git a/Tactility/Source/app/TileGrid.cpp b/Tactility/Source/app/TileGrid.cpp
index 01c0496db..8ed110ddd 100644
--- a/Tactility/Source/app/TileGrid.cpp
+++ b/Tactility/Source/app/TileGrid.cpp
@@ -90,6 +90,40 @@ void updatePageIndicatorWidth(void* data) {
     }
 }
 
+// A page indicator below the grid gets the width of its parent.
+// It shows the page number when its dots are wider than its max width, which must be in pixels.
+void updateCenteredPageIndicatorWidth(lv_obj_t* indicator) {
+    const int32_t margins = lv_obj_get_style_margin_left(indicator, LV_PART_MAIN) + lv_obj_get_style_margin_right(indicator, LV_PART_MAIN);
+    const int32_t max_width = std::max<int32_t>(0, lv_obj_get_content_width(lv_obj_get_parent(indicator)) - margins);
+    // Setting a style marks the layout as dirty, which would resize the parent and call this again
+    if (lv_obj_get_style_max_width(indicator, LV_PART_MAIN) != max_width) {
+        lv_obj_set_style_max_width(indicator, max_width, LV_STATE_DEFAULT);
+    }
+}
+
+void onCenteredPageIndicatorParentSizeChanged(lv_event_t* event) {
+    updateCenteredPageIndicatorWidth(static_cast<lv_obj_t*>(lv_event_get_user_data(event)));
+}
+
+void onCenteredPageIndicatorDeleted(lv_event_t* event) {
+    lv_obj_t* indicator = lv_event_get_target_obj(event);
+    lv_obj_remove_event_cb_with_user_data(lv_obj_get_parent(indicator), onCenteredPageIndicatorParentSizeChanged, indicator);
+}
+
+/** Call after moving the page indicator below the grid */
+void centerPageIndicator(lv_obj_t* indicator) {
+    lv_obj_set_width(indicator, LV_PCT(100));
+    lv_obj_add_event_cb(lv_obj_get_parent(indicator), onCenteredPageIndicatorParentSizeChanged, LV_EVENT_SIZE_CHANGED, indicator);
+    lv_obj_add_event_cb(indicator, onCenteredPageIndicatorDeleted, LV_EVENT_DELETE, nullptr);
+    updateCenteredPageIndicatorWidth(indicator);
+}
+
+/** Call before moving the page indicator away from below the grid */
+void uncenterPageIndicator(lv_obj_t* indicator) {
+    lv_obj_remove_event_cb_with_user_data(lv_obj_get_parent(indicator), onCenteredPageIndicatorParentSizeChanged, indicator);
+    lv_obj_remove_event_cb(indicator, onCenteredPageIndicatorDeleted);
+}
+
 void onBottomBarSizeChanged(lv_event_t* event) {
     lv_async_call_cancel(updatePageIndicatorWidth, lv_event_get_target_obj(event));
     lv_async_call(updatePageIndicatorWidth, lv_event_get_target_obj(event));
@@ -448,7 +482,7 @@ void TileGrid::createWidgets(lv_obj_t* parent) {
     createGrid(parent);
     // Centered below the grid
     pageIndicator = lvgl_page_indicator_create(parent);
-    lv_obj_set_width(pageIndicator, LV_PCT(100));
+    centerPageIndicator(pageIndicator);
     // Keeps the dots off the screen's bottom edge
     lv_obj_set_style_margin_bottom(pageIndicator, lvgl_theme_is_compact() ? LV_DPX(2) : LV_DPX(8), LV_STATE_DEFAULT);
     finishCreate(parent);
@@ -531,8 +565,7 @@ void TileGrid::setBarSideContainer(lv_obj_t* sideContainer) {
         // The page indicator is centered below the grid
         lv_obj_set_parent(pageIndicator, barParent);
         lv_obj_move_to_index(pageIndicator, lv_obj_get_index(grid) + 1);
-        lv_obj_set_width(pageIndicator, LV_PCT(100));
-        lv_obj_remove_local_style_prop(pageIndicator, LV_STYLE_MAX_WIDTH, LV_PART_MAIN);
+        centerPageIndicator(pageIndicator);
         // Keeps the dots off the screen's bottom edge
         lv_obj_set_style_margin_bottom(pageIndicator, lvgl_theme_is_compact() ? 1 : 2, LV_STATE_DEFAULT);
     } else {
@@ -543,9 +576,13 @@ void TileGrid::setBarSideContainer(lv_obj_t* sideContainer) {
         lv_obj_remove_local_style_prop(bottomBar, LV_STYLE_BG_OPA, LV_PART_MAIN);
         lv_obj_remove_local_style_prop(bottomBar, LV_STYLE_PAD_ROW, LV_PART_MAIN);
         lv_obj_set_hidden(barSpacer, false);
+        uncenterPageIndicator(pageIndicator);
         lv_obj_set_parent(pageIndicator, bottomBar);
         lv_obj_set_width(pageIndicator, LV_SIZE_CONTENT);
         lv_obj_remove_local_style_prop(pageIndicator, LV_STYLE_MARGIN_BOTTOM, LV_PART_MAIN);
+        // The bar's size can stay the same, which wouldn't update the max width
+        lv_async_call_cancel(updatePageIndicatorWidth, bottomBar);
+        lv_async_call(updatePageIndicatorWidth, bottomBar);
     }
     // The keys move through the bar where it's shown: below the statusbar's icons in the side strip, or below the grid
     setGroupOrder(grid, bottomBar, sideContainer != nullptr);
diff --git a/Tactility/Source/app/timezone/TimeZoneView.cpp b/Tactility/Source/app/timezone/TimeZoneView.cpp
index dcd758e67..2ddc341a2 100644
--- a/Tactility/Source/app/timezone/TimeZoneView.cpp
+++ b/Tactility/Source/app/timezone/TimeZoneView.cpp
@@ -78,6 +78,7 @@ TimeZoneView::TimeZoneView(OnSelected onSelected) : onSelected(std::move(onSelec
 
 TimeZoneView::~TimeZoneView() {
     filterTimer->stop();
+    cancelled = true;
     if (detectThread != nullptr) {
         detectThread->join();
     }
@@ -268,7 +269,16 @@ void TimeZoneView::detect() {
         failure = "The time zone couldn't be detected. Check the internet connection and try again.";
     }
 
-    lvgl_lock();
+    // Waits for the LVGL lock without blocking the destructor, which can be called with the lock held
+    while (!lvgl_try_lock(pdMS_TO_TICKS(50))) {
+        if (cancelled) {
+            return;
+        }
+    }
+    if (cancelled) {
+        lvgl_unlock();
+        return;
+    }
     detecting = false;
     mutex.lock();
     message = failure;
diff --git a/tt.py b/tt.py
index f05ce0820..b15e27d45 100755
--- a/tt.py
+++ b/tt.py
@@ -20,7 +20,7 @@ import time
 import urllib.request
 import zipfile
 
-TT_VERSION = "1.1.0"
+TT_VERSION = "1.1.1"
 CDN_URL = os.environ.get("TT_CDN", "https://cdn.tactilityproject.org")
 HOME_DIRECTORY = os.path.join(os.path.expanduser("~"), ".tactility")
 INDEX_VALIDITY_SECONDS = 3600
@@ -173,15 +173,47 @@ def install_platforms(version, version_directory, index, platforms):
             file.write(index.get("gitCommit", ""))
 
 
+def read_text(path):
+    try:
+        with open(path) as file:
+            return file.read().strip()
+    except OSError:
+        return None
+
+
+def is_installed_build(version_directory, index):
+    """True when the installed tools and platforms are of the build that the index describes"""
+    installed_tools_hash = read_text(os.path.join(version_directory, "tools.sha256"))
+    if installed_tools_hash is not None and installed_tools_hash != index.get("tools", {}).get("sha256"):
+        return False
+    for name in os.listdir(version_directory):
+        commit = read_text(os.path.join(version_directory, name, "commit"))
+        if name.startswith("platform-") and commit is not None and commit != index.get("gitCommit", ""):
+            return False
+    return True
+
+
 def prepare_sdk(version, platforms):
     """Installs what's missing of the SDK version. Installed tools and platforms are only replaced by "tt update-sdk", so they stay from the same build."""
     version_directory = version_path(HOME_DIRECTORY, version)
+    index = None
+    # "target.platforms=all" means every platform of the SDK
+    if platforms == ["all"]:
+        os.makedirs(version_directory, exist_ok=True)
+        index = load_index(version, version_directory)
+        platforms = sorted(index.get("platforms", {}))
     has_tools = os.path.isdir(os.path.join(version_directory, "tools"))
     missing_platforms = [platform for platform in platforms if not os.path.isdir(os.path.join(version_directory, f"platform-{platform}", "TactilitySDK"))]
     if has_tools and not missing_platforms:
         return version_directory
     os.makedirs(version_directory, exist_ok=True)
-    index = load_index(version, version_directory)
+    if index is None:
+        index = load_index(version, version_directory)
+    # The CDN only has the latest build of a version, so a newer build can't be mixed with the installed one
+    if not is_installed_build(version_directory, index):
+        if has_tools:
+            fail(f"SDK {version} was published again since it was installed: run 'tt update-sdk' first")
+        fail(f"SDK {version} was published again since it was installed: remove {version_directory} and try again")
     if not has_tools:
         install_tools(version, version_directory, index)
     install_platforms(version, version_directory, index, missing_platforms)
@@ -255,7 +287,9 @@ def main(arguments):
             fail(f"tools not found: {tools_directory}")
     else:
         sdk_path = HOME_DIRECTORY
-        tools_directory = os.path.join(prepare_sdk(version, platforms), "tools")
+        # update-sdk replaces the installed build, so it only needs the tools
+        required_platforms = [] if command == "update-sdk" else platforms
+        tools_directory = os.path.join(prepare_sdk(version, required_platforms), "tools")
     environment = tool_environment(version, sdk_path, is_local)
     if is_help:
         print_help(version, tools_directory)