diff --git a/install.ps1 b/install.ps1
index 4ab6b372f..dc3d0c50b 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 = "61176387d38c67e596c1669fee2bb3b981333ab0b808dd2e280a5a3870957738"
+    $defaultInstallSha256 = "e9bfce57f1aab1123937498d7ed7913223762df755bb572b9a36f2d6a69b7a55"
     # The pin above refuses any changed byte: this cap only stops a body that
     # cannot be the installer (a sign-in portal's page) before it is hashed.
     $maximumInstallerBytes = 8MB
diff --git a/install.py b/install.py
index 13d713275..5dab26d55 100644
--- a/install.py
+++ b/install.py
@@ -4423,9 +4423,9 @@ def fetch_manifest(plat: str) -> dict:
             # request, so the revision is what has no such list.
             print(f"  No file list for {plat} at {RELEASE_REF}.", file=sys.stderr)
             if RELEASE_REF != DEFAULT_RELEASE_REF:
-                print(f"  RETROBIOS_REF={RELEASE_REF} names a tag that does not exist or "
-                      f"predates {plat}: unset RETROBIOS_REF, or pick a tag from "
-                      "https://github.com/Abdess/retrobios/releases.", file=sys.stderr)
+                print(f"  RETROBIOS_REF={RELEASE_REF} has no list for {plat}: unset it, or "
+                      "pick a newer tag from https://github.com/Abdess/retrobios/releases.",
+                      file=sys.stderr)
             else:
                 print("  The repository may be moving its files: run the same command "
                       "again in a few minutes.", file=sys.stderr)
@@ -4441,9 +4441,9 @@ def fetch_manifest(plat: str) -> dict:
                     message=words if code != "network"
                     else f"the file list could not be fetched: {words}")
         if code == "offline":
-            print(f"  No file list for {plat}: {offline_words()}. Give it with "
-                  f"--manifest FILE (a copy of install/{plat}.json) or "
-                  f"--from-pack PACK, or run {offline_undo()}.", file=sys.stderr)
+            print(f"  No file list for {plat}: {offline_words()}. Give --manifest FILE "
+                  f"(a copy of install/{plat}.json) or --from-pack PACK, or run "
+                  f"{offline_undo()}.", file=sys.stderr)
             sys.exit(1)
         if code != "network":
             print(f"  Could not fetch the file list for {plat}.", file=sys.stderr)
@@ -4502,9 +4502,9 @@ def fetch_targets(plat: str) -> "dict | None":
     if LOCAL.offline:
         source = (f"{LOCAL.pack.name} carries none" if LOCAL.pack is not None
                   else f"{offline_named()} makes no request")
-        print(f"Error: --target reads the cores of each {display_name(plat)} board from a "
-              f"list, and {source}. Put install/targets/{plat}.json beside the file list "
-              "named with --manifest, or run with the network.", file=sys.stderr)
+        print(f"Error: no {display_name(plat)} board list here ({source}). Put "
+              f"install/targets/{plat}.json beside the --manifest file, or go online.",
+              file=sys.stderr)
         sys.exit(2)
     url = TARGETS_URL.format(platform=plat)
     try:
@@ -14011,9 +14011,8 @@ def main() -> None:
             and not (named and named not in TARGET_PLATFORMS)):
         # No list can be at hand: a pack carries one, and so can the folder
         # of a --manifest (targets/<platform>.json).
-        parser.error("--target and --list-targets read a core list from the network, "
-                     f"which {offline_named()} does not use: name a pack with --from-pack, "
-                     "or a file list with --manifest and targets/<platform>.json beside it")
+        parser.error(f"--target needs a core list, which {offline_named()} does not fetch: "
+                     "give --from-pack, or --manifest with targets/<platform>.json beside it")
     install_bounded_opener()
     if getattr(args, "from") and (
         args.list_platforms or args.list_targets or args.list_systems
@@ -15207,8 +15206,7 @@ def card_install_dest(named: str, plat: str, interactive: bool, ask: bool = True
                     message=f"{system} keeps its BIOS files on its SD card, and no "
                     "card was named with --dest")
         print(f"  {system} keeps its BIOS files on its SD card, not on this machine. "
-              f"Mount the card and name its root with --dest, for example: {example}",
-              file=sys.stderr)
+              f"Mount it and give its root with --dest: {example}", file=sys.stderr)
         sys.exit(1)
     print(f"  {system} keeps its BIOS files {card_where(system, setup.below)}, not on "
           "this machine. "
@@ -15393,9 +15391,8 @@ def _install(args: argparse.Namespace, real_stdout: TextIO) -> None:
             kind = _output_kind(real_stdout)
             where = f"Output goes to a {kind}" if kind else "Output is not a terminal"
             undo = "the pipe" if kind == "pipe" else "the redirection"
-            print(f"{where}, so nothing is asked: the run goes on as with --no-input. "
-                  f"Add --no-input to say so, or run it without {undo} to answer.",
-                  file=sys.stderr)
+            print(f"{where}, so nothing is asked. Add --no-input to say so, or run it "
+                  f"without {undo} to answer.", file=sys.stderr)
     OUTPUT.verbose = bool(getattr(args, "verbose", False))
     OUTPUT.where_said = False
     detail(f"{term.bold('RetroBIOS')} {term.dim(installer_id())}\n")
diff --git a/install.sh b/install.sh
index c8bdfb3e8..92e49ff45 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="61176387d38c67e596c1669fee2bb3b981333ab0b808dd2e280a5a3870957738"
+DEFAULT_INSTALL_SHA256="e9bfce57f1aab1123937498d7ed7913223762df755bb572b9a36f2d6a69b7a55"
 # The pin above refuses any changed byte: this cap only stops a body that
 # cannot be the installer (a sign-in portal's page) before it is hashed.
 MAX_INSTALLER_BYTES=8388608
diff --git a/install/launchers/index.json b/install/launchers/index.json
index 2bd3d1a2b..5f955c7bf 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": 1143258,
-          "sha256": "61176387d38c67e596c1669fee2bb3b981333ab0b808dd2e280a5a3870957738",
+          "size": 1142976,
+          "sha256": "e9bfce57f1aab1123937498d7ed7913223762df755bb572b9a36f2d6a69b7a55",
           "executable": false
         },
         {
@@ -71,8 +71,8 @@
     "muos": {
       "archive": {
         "dest": "ARCHIVE/RetroBIOS.muxapp",
-        "size": 1196883,
-        "sha256": "2c84115b87ed4bcd4fdf4d64d56fc1221485cbd9822cfeb0770b07b9b4226e51"
+        "size": 1196601,
+        "sha256": "9305dd087110937f9c4c2d08cf4b52aa55dc0c8835109991f913e23ca30f3926"
       },
       "members": [
         {
@@ -92,8 +92,8 @@
         {
           "name": "RetroBIOS/install.py",
           "repo_path": "install.py",
-          "size": 1143258,
-          "sha256": "61176387d38c67e596c1669fee2bb3b981333ab0b808dd2e280a5a3870957738",
+          "size": 1142976,
+          "sha256": "e9bfce57f1aab1123937498d7ed7913223762df755bb572b9a36f2d6a69b7a55",
           "executable": false
         },
         {
@@ -166,8 +166,8 @@
         {
           "dest": ".config/modules/retrobios/install.py",
           "repo_path": "install.py",
-          "size": 1143258,
-          "sha256": "61176387d38c67e596c1669fee2bb3b981333ab0b808dd2e280a5a3870957738",
+          "size": 1142976,
+          "sha256": "e9bfce57f1aab1123937498d7ed7913223762df755bb572b9a36f2d6a69b7a55",
           "executable": false
         },
         {
diff --git a/tests/test_install.py b/tests/test_install.py
index cd75993d7..a6d974726 100644
--- a/tests/test_install.py
+++ b/tests/test_install.py
@@ -7677,5 +7677,34 @@ class APackageHintNamesThePackageCommand(unittest.TestCase):
                 "uvx retrobios --platform retroarch --dest DIR"))
 
 
+class AnErrorIsOneShortSentence(unittest.TestCase):
+    """A message on stderr says what to do in a few words: one of 35 words
+    asked a beginner to read a paragraph to find the option to give."""
+
+    BUDGET = 25
+
+    def test_every_stderr_message_is_short(self):
+        import ast
+
+        tree = ast.parse((REPO_ROOT / "install.py").read_text(encoding="utf-8"))
+        long = []
+        for node in ast.walk(tree):
+            if not isinstance(node, ast.Call):
+                continue
+            name = getattr(node.func, "id", getattr(node.func, "attr", ""))
+            to_err = any(k.arg == "file" and "stderr" in ast.unparse(k.value)
+                         for k in node.keywords)
+            if not (to_err or name == "error"):
+                continue
+            text = " ".join(ast.unparse(a) for a in node.args)
+            if ".command(" in text:
+                continue
+            prose = re.sub(r"\{[^}]*\}", "X", text)
+            words = len(re.findall(r"[A-Za-z']+", prose))
+            if words > self.BUDGET:
+                long.append((node.lineno, words))
+        self.assertEqual(long, [])
+
+
 if __name__ == "__main__":
     unittest.main()