diff --git a/400_xowa/src/gplx/xowa/Xowe_wiki.java b/400_xowa/src/gplx/xowa/Xowe_wiki.java
index 6833f8b43..9ec6e0e40 100644
--- a/400_xowa/src/gplx/xowa/Xowe_wiki.java
+++ b/400_xowa/src/gplx/xowa/Xowe_wiki.java
@@ -126,6 +126,7 @@ public class Xowe_wiki implements Xow_wiki, Gfo_invk, Gfo_evt_itm {
 	public byte[]					Wtxt__expand_tmpl(byte[] src) {return parser_mgr.Main().Expand_tmpl(src);}
 	public boolean                  Embeddable_enabled() {return embeddable_enabled;} public void Embeddable_enabled_(boolean v) {this.embeddable_enabled = v;} private boolean embeddable_enabled;
 	public Hxtn_page_mgr            Hxtn_mgr() {return hxtn_mgr;} private final    Hxtn_page_mgr hxtn_mgr = new Hxtn_page_mgr();
+	public boolean                  Installed() {return this.Data__core_mgr() != null;} // not sure if this is the best way
 
 	public Xow_hdump_mgr			Html__hdump_mgr() {return html__hdump_mgr;} private final    Xow_hdump_mgr html__hdump_mgr;
 	public Xoae_app					Appe() {return app;} private Xoae_app app;
diff --git a/400_xowa/src/gplx/xowa/apps/servers/http/Http_server_page.java b/400_xowa/src/gplx/xowa/apps/servers/http/Http_server_page.java
index 8adf38a45..7225a7122 100644
--- a/400_xowa/src/gplx/xowa/apps/servers/http/Http_server_page.java
+++ b/400_xowa/src/gplx/xowa/apps/servers/http/Http_server_page.java
@@ -40,6 +40,11 @@ public class Http_server_page {
 	public boolean Make_url(byte[] wiki_domain, byte[] ttl_bry_arg, byte[] qarg) {
 		// get wiki
 		wiki = (Xowe_wiki)app.Wiki_mgr().Get_by_or_make_init_y(wiki_domain); // assert init for Main_Page; EX:click zh.w on wiki sidebar; DATE:2015-07-19
+		if (!wiki.Installed()) {
+			this.ttl = wiki.Ttl_parse(Xow_special_meta_.Itm__error.Ttl_bry());
+			this.url = wiki.Utl__url_parser().Parse(Xoerror_special.Make_url__invalidWiki(wiki_domain));
+			return true;
+		}
 		if (Runtime_.Memory_total() > Io_mgr.Len_gb) Xowe_wiki_.Rls_mem(wiki, true); // release memory at 1 GB; DATE:2015-09-11
 
 		// get url
diff --git a/400_xowa/src/gplx/xowa/specials/xowa/errors/Xoerror_special.java b/400_xowa/src/gplx/xowa/specials/xowa/errors/Xoerror_special.java
index 6b004e915..29b6e25c7 100644
--- a/400_xowa/src/gplx/xowa/specials/xowa/errors/Xoerror_special.java
+++ b/400_xowa/src/gplx/xowa/specials/xowa/errors/Xoerror_special.java
@@ -31,6 +31,10 @@ public class Xoerror_special implements Xow_special_page {
 			title = "Invalid title";
 			msg = "The title has invalid characters: <span style='color:red;font-weight:bold'>" + data + "</span>";
 		}
+		else if (String_.Eq(type, "InvalidWiki")) {
+			title = "Invalid wiki";
+			msg = "The wiki is not installed: <span style='color:red;font-weight:bold'>" + data + "</span>";
+		}
 
 		page.Db().Text().Text_bry_(fmt.Bld_many_to_bry(Bry_bfr_.New(), title, msg));
 	}
@@ -41,7 +45,10 @@ public class Xoerror_special implements Xow_special_page {
 	));
 
 	public Xow_special_page Special__clone() {return this;}
-	public static byte[] Make_url__invalidTitle(byte[] invalid_title) {
-		return Bry_.Add(Xow_special_meta_.Itm__error.Ttl_bry(), Bry_.new_a7("?type=InvalidTitle&data="), invalid_title);
+	public static byte[] Make_url__invalidTitle(byte[] ttl_bry) {
+		return Bry_.Add(Xow_special_meta_.Itm__error.Ttl_bry(), Bry_.new_a7("?type=InvalidTitle&data="), ttl_bry);
+	}
+	public static byte[] Make_url__invalidWiki(byte[] wiki) {
+		return Bry_.Add(Xow_special_meta_.Itm__error.Ttl_bry(), Bry_.new_a7("?type=InvalidWiki&data="), wiki);
 	}
 }