diff --git a/install.ps1 b/install.ps1
index 48f2ca54b..37de60804 100644
--- a/install.ps1
+++ b/install.ps1
@@ -16,7 +16,7 @@
     # and Invoke-WebRequest throws on a cut transfer before the hash is read:
     # the site's build rewrites this line there (scripts/sitebootstrap.py).
     $mismatchAdvice = "The download was most likely cut short: try again. Within minutes of an update of this project the two files can come from caches of different ages. Waiting five minutes settles that."
-    $defaultInstallSha256 = "627e9c3bb72daacae022a93f5ca2ba010cd8fb025ef92d69f020734575ee9bad"
+    $defaultInstallSha256 = "7cbbbe3baefc4a03f5e8a85ee915df4ae23217d21aa61a2dcfccb4cbc846f546"
     $maximumInstallerBytes = 2MB
     $installerExit = 0
     $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }
diff --git a/install.py b/install.py
index 21dcb64d4..a46e1e478 100644
--- a/install.py
+++ b/install.py
@@ -9233,6 +9233,7 @@ class GamesData:
             raw = _read_capped(beside / "index.json", MAX_GAMES_INDEX_BYTES)
         cached = self.cached("index.json")
         reason = "offline"
+        failure = ""
         if raw is None and network:
             try:
                 raw = _fetch_json(GAMES_URL.format(path="index.json"), MAX_GAMES_INDEX_BYTES,
@@ -9242,8 +9243,7 @@ class GamesData:
             except (urllib.error.URLError, OSError, ValueError,
                     http.client.HTTPException) as exc:
                 reason = "network"
-                if os.environ.get("RETROBIOS_DEBUG"):
-                    print(f"  Games index: {exc}", file=sys.stderr)
+                failure = str(exc)
             else:
                 if cached is not None:
                     _cache_write(cached, raw)
@@ -9252,7 +9252,8 @@ class GamesData:
         if raw is None:
             raise GamesUnavailable(reason, (
                 f"the games index is not on this machine and {offline_words()}"
-                if reason == "offline" else "the games index could not be downloaded"))
+                if reason == "offline"
+                else f"the games index could not be downloaded ({failure})"))
         try:
             data = json.loads(raw.decode("utf-8"))
         except (UnicodeDecodeError, json.JSONDecodeError) as exc:
diff --git a/install.sh b/install.sh
index 7e3eb0e3f..8555cd2c6 100755
--- a/install.sh
+++ b/install.sh
@@ -23,7 +23,7 @@ DEFAULT_INSTALL_URL="https://raw.githubusercontent.com/Abdess/retrobios/main/ins
 # curl or wget stop on a cut transfer before the hash is read: the site's
 # build rewrites this line there (scripts/sitebootstrap.py).
 MISMATCH_ADVICE="The download was most likely cut short: try again. Within minutes of an update of this project the two files can come from caches of different ages. Waiting five minutes settles that."
-DEFAULT_INSTALL_SHA256="627e9c3bb72daacae022a93f5ca2ba010cd8fb025ef92d69f020734575ee9bad"
+DEFAULT_INSTALL_SHA256="7cbbbe3baefc4a03f5e8a85ee915df4ae23217d21aa61a2dcfccb4cbc846f546"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {
diff --git a/install/launchers/index.json b/install/launchers/index.json
index 45856d1f4..4aaafb661 100644
--- a/install/launchers/index.json
+++ b/install/launchers/index.json
@@ -27,8 +27,8 @@
         {
           "dest": "roms/ports/retrobios/install.py",
           "repo_path": "install.py",
-          "size": 1080043,
-          "sha256": "627e9c3bb72daacae022a93f5ca2ba010cd8fb025ef92d69f020734575ee9bad",
+          "size": 1080006,
+          "sha256": "7cbbbe3baefc4a03f5e8a85ee915df4ae23217d21aa61a2dcfccb4cbc846f546",
           "executable": false
         },
         {
@@ -71,8 +71,8 @@
     "muos": {
       "archive": {
         "dest": "ARCHIVE/RetroBIOS.muxapp",
-        "size": 1133220,
-        "sha256": "818f6453e8c441729b395a765f47735d5c3710a03db288ab5609b4485710d2cd"
+        "size": 1133183,
+        "sha256": "cc752f0ea8becaba5f3d96c6c77ca9c39b8b870fd9d2019985e1fd78ed912592"
       },
       "members": [
         {
@@ -92,8 +92,8 @@
         {
           "name": "RetroBIOS/install.py",
           "repo_path": "install.py",
-          "size": 1080043,
-          "sha256": "627e9c3bb72daacae022a93f5ca2ba010cd8fb025ef92d69f020734575ee9bad",
+          "size": 1080006,
+          "sha256": "7cbbbe3baefc4a03f5e8a85ee915df4ae23217d21aa61a2dcfccb4cbc846f546",
           "executable": false
         },
         {
@@ -166,8 +166,8 @@
         {
           "dest": ".config/modules/retrobios/install.py",
           "repo_path": "install.py",
-          "size": 1080043,
-          "sha256": "627e9c3bb72daacae022a93f5ca2ba010cd8fb025ef92d69f020734575ee9bad",
+          "size": 1080006,
+          "sha256": "7cbbbe3baefc4a03f5e8a85ee915df4ae23217d21aa61a2dcfccb4cbc846f546",
           "executable": false
         },
         {
diff --git a/tests/test_install_games.py b/tests/test_install_games.py
index f5c98ce54..117970364 100644
--- a/tests/test_install_games.py
+++ b/tests/test_install_games.py
@@ -22,6 +22,7 @@ import sys
 import tempfile
 import threading
 import unittest
+import urllib.error
 import zipfile
 import zlib
 from pathlib import Path
@@ -777,6 +778,18 @@ class Unavailable(GamesTestCase):
             install.plan_games("retroarch", self.card.bios, manifest(), os_type="linux")
         self.assertEqual(caught.exception.reason, "offline")
 
+    def test_a_failed_download_says_why(self):
+        """The cause was printed only under RETROBIOS_DEBUG: a proxy's 403
+        or a TLS refusal read as a bare "could not be downloaded"."""
+        shutil.rmtree(self.card.lists / "games")
+        refusal = urllib.error.HTTPError(
+            "https://example.invalid/index.json", 403, "Forbidden", {}, None)
+        with mock.patch.object(install, "_fetch_json", side_effect=refusal), \
+                self.assertRaises(install.GamesUnavailable) as caught:
+            install.GamesData().load_index(network=True, attempts=1)
+        self.assertEqual(caught.exception.reason, "network")
+        self.assertIn("403", caught.exception.words)
+
     def test_a_document_that_is_not_the_one_listed_is_refused(self):
         (self.card.lists / "games" / "setups" / "retroarch.json").write_text("{}")
         with self.assertRaises(install.GamesUnavailable) as caught: