@@ -63,7 +63,12 @@ JDK, so `java` can only come from what vfox installs:
    registered from this checkout. On Windows, the runner builds `main` once,
    while the `latest` combinations run, and the `main` containers start from
    the e2e image plus that `vfox.exe`.
-2. A release no distribution has published (`<major>.0.99`) fails to install,
+2. A distribution without a version, alone or after an empty one
+   (`java@tem`, `java@-tem`), fails both `vfox install` and `vfox use` with
+   an error asking for one. The hooks stopped with a Lua error on the first,
+   while `PreInstall` sent the empty version to Foojay, which lists every
+   release, and installed the newest one.
+   A release no distribution has published (`<major>.0.99`) fails to install,
    with `PreInstall` naming the platform it searched (`linux/amd64`,
    `windows/arm64`, ...), so the Foojay lookup is checked to target the
    runner. So does a build of the pinned release that was never published
 
@@ -83,7 +83,11 @@ function PLUGIN:ParseLegacyFile(ctx)
     if not distributionVersion then
         return {}
     end
+    --- A distribution alone (java=tem) selects nothing, as vfox use rejects it.
     local fullVersion = distributionVersion.version
+    if not fullVersion then
+        return {}
+    end
     local vendor = distributionVersion.distribution.short_name
     if not vendor then
         return {}
 
@@ -30,6 +30,9 @@ function PLUGIN:PreInstall(ctx)
     if not distribution_version then
         error("Could not extract a valid distribution: " .. ctx.version)
     end
+    if not distribution_version.version then
+        error(distribution_version_parser.missing_version_error(ctx.version, distribution_version))
+    end
     if loongnix.supported() or loongnix.is_distribution(distribution_version.distribution.name) then
         return loongnix.pre_install(distribution_version)
     end
 
@@ -29,6 +29,9 @@ function PLUGIN:PreUse(ctx)
     end
 
     if distribution_version then
+        if not distribution_version.version then
+            error(distribution_version_parser.missing_version_error(input_version, distribution_version))
+        end
         -- OpenJDK versions are installed without a distribution suffix, so
         -- 25.0.2+10-open and openjdk-25.0.2+10 both name 25.0.2+10.
         local suffix = distribution_version.javafx_bundled and "-fx" or ""
 
@@ -130,8 +130,15 @@ function distribution_version.parse_version(arg)
         end
     end
 
-    -- Convert version format for Foojay API
-    version = distribution_version.convert_version_for_api(version)
+    -- A distribution alone (tem, zulu-fx), or after an empty version (-tem,
+    -- temurin-), names no version: leave it nil for the hooks to reject.
+    if version == "" then
+        version = nil
+    end
+    if version then
+        -- Convert version format for Foojay API
+        version = distribution_version.convert_version_for_api(version)
+    end
 
     return {
         version = version,
@@ -140,4 +147,21 @@ function distribution_version.parse_version(arg)
     }
 end
 
+--- Returns the error for a user-input version that parse_version read
+--- without a version, such as tem: it names no JDK to install or use.
+--- @param arg string User-input version
+--- @param parsed table What parse_version returned for arg
+--- @return string Error message
+function distribution_version.missing_version_error(arg, parsed)
+    local short_name = parsed.distribution.short_name
+    return "No version in "
+        .. arg
+        .. "; add one, such as 21-"
+        .. short_name
+        .. (parsed.javafx_bundled and "-fx" or "")
+        .. ". Please check available versions with 'vfox search java "
+        .. short_name
+        .. "'"
+end
+
 return distribution_version
@@ -260,6 +260,16 @@ func MissingBuildSpec(distribution, version string) string {
 	return Spec(distribution, version+"+99")
 }
 
+// VersionlessSpecs renders the distribution without a version, alone and
+// after an empty one ("tem" and "-tem", "librca-fx" and "-librca-fx", "open"
+// and "-open" for OpenJDK). PreInstall and PreUse must reject both, asking
+// for a version: they failed with a Lua error on the first (vfox-java#98),
+// while PreInstall sent the empty version to Foojay, which lists every
+// release, and installed the newest one.
+func VersionlessSpecs(distribution string) []string {
+	return []string{distribution, "-" + distribution}
+}
+
 // Decoy renders the installed name of another release whose version starts
 // with the pinned one (<version>0+1, e.g. 21.0.80+1-tem). vfox lists the
 // installed versions sorted as strings, descending, so it comes before the
 
@@ -209,6 +209,21 @@ func TestSpecs(t *testing.T) {
 	}
 }
 
+func TestVersionlessSpecs(t *testing.T) {
+	for _, c := range []struct {
+		dist string
+		want []string
+	}{
+		{"open", []string{"open", "-open"}},
+		{"tem", []string{"tem", "-tem"}},
+		{"librca-fx", []string{"librca-fx", "-librca-fx"}},
+	} {
+		if got := VersionlessSpecs(c.dist); !slices.Equal(got, c.want) {
+			t.Errorf("VersionlessSpecs(%s) = %q, want %q", c.dist, got, c.want)
+		}
+	}
+}
+
 func TestPaddedIdentifier(t *testing.T) {
 	for _, c := range []struct{ dist, version, installed, want string }{
 		{"open", "25.0.2", "25.0.2+10", "25.0.2.0+10-open"},
 
@@ -166,6 +166,7 @@ func runOne(t *testing.T, ctx context.Context, image, platform, arch string, c c
 	t.Logf("=== vfox %s, java@%s, %s (%s) ===", c.Vfox, common.Spec(c.Distribution, version), platform, machine)
 
 	setupVfox(ctx, t, ctr, c.Vfox)
+	checkVersionlessRejected(ctx, t, ctr, c.Distribution)
 	checkMissingVersionRejected(ctx, t, ctr, c.Distribution, version, arch)
 
 	installed := installJava(ctx, t, ctr, common.Spec(c.Distribution, version))
 
@@ -51,6 +51,26 @@ func setupVfox(ctx context.Context, t *testing.T, ctr tc.Container, vfoxVersion
 	t.Logf("PASS %s with the local java plugin", strings.TrimSpace(execOK(ctx, t, ctr, "vfox --version")))
 }
 
+// checkVersionlessRejected proves a distribution without a version (e.g.
+// java@tem, java@-tem, see common.VersionlessSpecs) fails both `vfox
+// install` and `vfox use` with an error asking for one. The hooks raise it
+// before any Foojay lookup, so nothing is retried.
+func checkVersionlessRejected(ctx context.Context, t *testing.T, ctr tc.Container, distribution string) {
+	t.Helper()
+	for _, spec := range common.VersionlessSpecs(distribution) {
+		want := "No version in " + spec + ";"
+		for _, c := range []struct{ label, script string }{
+			{"vfox install java@" + spec, "vfox install java@" + spec},
+			{"vfox use --global java@" + spec, activated("vfox use --global java@" + spec)},
+		} {
+			code, out := execRun(ctx, t, ctr, c.script)
+			require.NotZerof(t, code, "%s must fail\n--- output ---\n%s", c.label, out)
+			require.Containsf(t, common.StripANSI(out), want, "%s must ask for a version", c.label)
+		}
+		t.Logf("PASS java@%s is rejected by vfox install and vfox use", spec)
+	}
+}
+
 // checkMissingVersionRejected proves an unpublished release, and an
 // unpublished build of the pinned one, fail loudly instead of installing
 // something else: PreInstall finds no Foojay package and names the platform
 
@@ -242,9 +242,10 @@ func runOne(t *testing.T, ctx context.Context, image, platform, arch string, c c
 
 	box := setupSlotEnv(ctx, t, ctr, c.Slug())
 	setupVfox(ctx, t, ctr, box, c.Vfox)
+	activation := fetchActivation(ctx, t, ctr, box)
+	checkVersionlessRejected(ctx, t, ctr, box, activation, c.Distribution)
 	checkMissingVersionRejected(ctx, t, ctr, box, c.Distribution, version, arch)
 
-	activation := fetchActivation(ctx, t, ctr, box)
 	installed := installJava(ctx, t, ctr, box, common.Spec(c.Distribution, version))
 	verifySearch(ctx, t, ctr, box, c.Distribution, installed)
 	// Before any `vfox use`, so java can only come from the legacy file.