handle cases where extensions don't exist.

aqt/archives.py

@@ -438,21 +438,33 @@ def _get_archives_base(self, name, target_packages):
                     "online/qtsdkrepository", os_name, "extensions", ext, self._version_str(), arch
                 )
                 extensions_xml_url = posixpath.join(extensions_target_folder, "Updates.xml")
-                extensions_xml_text = self._download_update_xml(extensions_xml_url)
-                update_xmls.append(UpdateXmls(extensions_target_folder, extensions_xml_text))
+                # The extension may or may not exist for this version and arch.
+                try:
+                    extensions_xml_text = self._download_update_xml(extensions_xml_url, True)
+                except ArchiveDownloadError:
+                    # In case _download_update_xml ignores the hash and tries to get the url.
+                    pass
+                if extensions_xml_text:
+                    self.logger.info("Found extension {}".format(ext))
+                    update_xmls.append(UpdateXmls(extensions_target_folder, extensions_xml_text))
 
         self._parse_update_xmls(update_xmls, target_packages)
 
-    def _download_update_xml(self, update_xml_path):
+    def _download_update_xml(self, update_xml_path, silent=False):
         """Hook for unit test."""
         if not Settings.ignore_hash:
             try:
                 xml_hash = get_hash(update_xml_path, Settings.hash_algorithm, self.timeout)
             except ChecksumDownloadFailure:
-                self.logger.warning(
-                    "Failed to download checksum for the file 'Updates.xml'. This may happen on unofficial mirrors."
-                )
-                xml_hash = None
+                if silent:
+                    return None
+                else:
+                    self.logger.warning(
+                        "Failed to download checksum for the file '{}'. This may happen on unofficial mirrors.".format(
+                            update_xml_path
+                        )
+                    )
+                    xml_hash = None
         else:
             xml_hash = None
         return getUrl(posixpath.join(self.base, update_xml_path), self.timeout, xml_hash)

aqt/metadata.py

@@ -37,7 +37,14 @@
 from semantic_version import Version as SemanticVersion
 from texttable import Texttable
 
-from aqt.exceptions import ArchiveConnectionError, ArchiveDownloadError, ArchiveListError, CliInputError, EmptyMetadata
+from aqt.exceptions import (
+    ArchiveConnectionError,
+    ArchiveDownloadError,
+    ArchiveListError,
+    ChecksumDownloadFailure,
+    CliInputError,
+    EmptyMetadata,
+)
 from aqt.helper import Settings, get_hash, getUrl, xml_to_modules
 
 
@@ -556,6 +563,12 @@ def is_in_wasm_range(host: str, version: Version) -> bool:
     def is_in_wasm_threaded_range(version: Version) -> bool:
         return version in SimpleSpec(">=6.5.0")
 
+    @staticmethod
+    def known_extensions(version: Version) -> List[str]:
+        if version >= Version("6.8.0"):
+            return ["qtpdf", "qtwebengine"]
+        return []
+
 
 class MetadataFactory:
     """Retrieve metadata of Qt variations, versions, and descriptions from Qt site."""
@@ -886,9 +899,19 @@ def to_module_arch(name: str) -> Tuple[Optional[str], Optional[str]]:
             module, _arch = to_module_arch(name)
             if _arch == arch:
                 modules.add(cast(str, module))
-        if version >= Version("6.8.0"):
-            for ext in self.fetch_extensions():
-                modules.add(ext)
+
+        ext_pattern = re.compile(r"^extensions\." + r"(?P<module>[^.]+)\." + qt_ver_str + r"\." + arch + r"$")
+        for ext in QtRepoProperty.known_extensions(version):
+            try:
+                ext_meta = self._fetch_extension_metadata(self.archive_id.to_extension_folder(ext, qt_ver_str, arch))
+                for key, value in ext_meta.items():
+                    ext_match = ext_pattern.match(key)
+                    if ext_match is not None:
+                        module = ext_match.group("module")
+                        if module is not None:
+                            modules.add(ext)
+            except (ChecksumDownloadFailure, ArchiveDownloadError):
+                pass
         return sorted(modules)
 
     @staticmethod
@@ -930,15 +953,17 @@ def matches_arch(element: Element) -> bool:
         # Examples: extensions.qtwebengine.680.debug_information
         #           extensions.qtwebengine.680.win64_msvc2022_64
         ext_pattern = re.compile(r"^extensions\." + r"(?P<module>[^.]+)\." + qt_ver_str + r"\." + arch + r"$")
-        if version >= Version("6.8.0"):
-            for ext in self.fetch_extensions():
+        for ext in QtRepoProperty.known_extensions(version):
+            try:
                 ext_meta = self._fetch_extension_metadata(self.archive_id.to_extension_folder(ext, qt_ver_str, arch))
                 for key, value in ext_meta.items():
                     ext_match = ext_pattern.match(key)
                     if ext_match is not None:
                         module = ext_match.group("module")
                         if module is not None:
                             m[module] = value
+            except (ChecksumDownloadFailure, ArchiveDownloadError):
+                pass
         return ModuleData(m)
 
     def fetch_modules_sde(self, cmd_type: str, version: Version) -> List[str]: