diff --git a/web/documentserver-example/csharp-mvc/Scripts/jscript.js b/web/documentserver-example/csharp-mvc/Scripts/jscript.js
index ca5a789d..520095a0 100644
--- a/web/documentserver-example/csharp-mvc/Scripts/jscript.js
+++ b/web/documentserver-example/csharp-mvc/Scripts/jscript.js
@@ -121,7 +121,7 @@ if (typeof jQuery != "undefined") {
         jq("#filePass").val("");
 
         var fileName = jq("#hiddenFileName").val();
-        var posExt = fileName.lastIndexOf('.');
+        var posExt = fileName.lastIndexOf('.') + 1;
         posExt = 0 <= posExt ? fileName.substring(posExt).trim().toLowerCase() : '';
 
         if (!formatManager.isAutoConvertible(posExt)) {
diff --git a/web/documentserver-example/csharp/script/jscript.js b/web/documentserver-example/csharp/script/jscript.js
index d64ff30b..5e9051c3 100644
--- a/web/documentserver-example/csharp/script/jscript.js
+++ b/web/documentserver-example/csharp/script/jscript.js
@@ -121,7 +121,7 @@ if (typeof jQuery != "undefined") {
         jq("#filePass").val("");
 
         var fileName = jq("#hiddenFileName").val();
-        var posExt = fileName.lastIndexOf('.');
+        var posExt = fileName.lastIndexOf('.') + 1;
         posExt = 0 <= posExt ? fileName.substring(posExt).trim().toLowerCase() : '';
 
         if (!formatManager.isAutoConvertible(posExt)) {
diff --git a/web/documentserver-example/python/static/js/jscript.js b/web/documentserver-example/python/static/js/jscript.js
index 4f4c0c06..fb67bff6 100644
--- a/web/documentserver-example/python/static/js/jscript.js
+++ b/web/documentserver-example/python/static/js/jscript.js
@@ -121,7 +121,7 @@ if (typeof jQuery !== "undefined") {
         jq("#filePass").val("");
 
         var fileName = jq("#hiddenFileName").val();
-        var posExt = fileName.lastIndexOf(".");
+        var posExt = fileName.lastIndexOf(".") + 1;
         posExt = 0 <= posExt ? fileName.substring(posExt).trim().toLowerCase() : "";
 
         if (!formatManager.isAutoConvertible(posExt)) {