diff -Nru smuxi-1.1+master.bzr537~ubuntu20.10.1/debian/bzr-builder.manifest smuxi-1.1+master.bzr538~ubuntu20.10.1/debian/bzr-builder.manifest
--- smuxi-1.1+master.bzr537~ubuntu20.10.1/debian/bzr-builder.manifest	2021-06-04 08:02:53.000000000 +0000
+++ smuxi-1.1+master.bzr538~ubuntu20.10.1/debian/bzr-builder.manifest	2021-06-08 18:32:05.000000000 +0000
@@ -1,2 +1,2 @@
-# bzr-builder format 0.3 deb-version 2:{debupstream}.bzr537
-lp:~meebey/smuxi/smuxi-head-mirror-stable revid:git-v1:d4afeaa3ed531f8c4572444727c71b43954fd489
+# bzr-builder format 0.3 deb-version 2:{debupstream}.bzr538
+lp:~meebey/smuxi/smuxi-head-mirror-stable revid:git-v1:fe430844e15a793289c3d1c92d88aef622405b76
diff -Nru smuxi-1.1+master.bzr537~ubuntu20.10.1/debian/changelog smuxi-1.1+master.bzr538~ubuntu20.10.1/debian/changelog
--- smuxi-1.1+master.bzr537~ubuntu20.10.1/debian/changelog	2021-06-04 08:02:53.000000000 +0000
+++ smuxi-1.1+master.bzr538~ubuntu20.10.1/debian/changelog	2021-06-08 18:32:05.000000000 +0000
@@ -1,8 +1,8 @@
-smuxi (2:1.1+master.bzr537~ubuntu20.10.1) groovy; urgency=low
+smuxi (2:1.1+master.bzr538~ubuntu20.10.1) groovy; urgency=low
 
   * Auto build.
 
- -- Mirco Bauer <meebey@gmail.com>  Fri, 04 Jun 2021 08:02:53 +0000
+ -- Mirco Bauer <meebey@gmail.com>  Tue, 08 Jun 2021 18:32:05 +0000
 
 smuxi (2:1.1+master-1) unstable; urgency=medium
 
diff -Nru smuxi-1.1+master.bzr537~ubuntu20.10.1/.pc/.quilt_patches smuxi-1.1+master.bzr538~ubuntu20.10.1/.pc/.quilt_patches
--- smuxi-1.1+master.bzr537~ubuntu20.10.1/.pc/.quilt_patches	2021-06-04 08:02:53.000000000 +0000
+++ smuxi-1.1+master.bzr538~ubuntu20.10.1/.pc/.quilt_patches	2021-06-08 18:32:05.000000000 +0000
@@ -1 +1 @@
-/home/buildd/build-RECIPEBRANCHBUILD-2810533/chroot-autobuild/home/buildd/work/tree/smuxi-1.1+master.bzr537~ubuntu20.10.1/debian/patches
+/home/buildd/build-RECIPEBRANCHBUILD-2813329/chroot-autobuild/home/buildd/work/tree/smuxi-1.1+master.bzr538~ubuntu20.10.1/debian/patches
diff -Nru smuxi-1.1+master.bzr537~ubuntu20.10.1/.pc/.quilt_series smuxi-1.1+master.bzr538~ubuntu20.10.1/.pc/.quilt_series
--- smuxi-1.1+master.bzr537~ubuntu20.10.1/.pc/.quilt_series	2021-06-04 08:02:53.000000000 +0000
+++ smuxi-1.1+master.bzr538~ubuntu20.10.1/.pc/.quilt_series	2021-06-08 18:32:05.000000000 +0000
@@ -1 +1 @@
-/home/buildd/build-RECIPEBRANCHBUILD-2810533/chroot-autobuild/home/buildd/work/tree/smuxi-1.1+master.bzr537~ubuntu20.10.1/debian/patches/series
+/home/buildd/build-RECIPEBRANCHBUILD-2813329/chroot-autobuild/home/buildd/work/tree/smuxi-1.1+master.bzr538~ubuntu20.10.1/debian/patches/series
diff -Nru smuxi-1.1+master.bzr537~ubuntu20.10.1/src/Engine/Config/ServerModel.cs smuxi-1.1+master.bzr538~ubuntu20.10.1/src/Engine/Config/ServerModel.cs
--- smuxi-1.1+master.bzr537~ubuntu20.10.1/src/Engine/Config/ServerModel.cs	2021-06-04 08:02:47.000000000 +0000
+++ smuxi-1.1+master.bzr538~ubuntu20.10.1/src/Engine/Config/ServerModel.cs	2021-06-08 18:31:55.000000000 +0000
@@ -229,8 +229,10 @@
             config[ConfigKeyPrefix + "UseEncryption"] = UseEncryption;
             config[ConfigKeyPrefix + "ValidateServerCertificate"] =
                 ValidateServerCertificate;
+            // ClientCertificateFilename is an internal setting which not
+            // exposed in the UI, thus the value remains null
             config[ConfigKeyPrefix + "ClientCertificateFilename"] =
-                ClientCertificateFilename;
+                ClientCertificateFilename ?? String.Empty;
             config[ConfigKeyPrefix + "OnStartupConnect"] = OnStartupConnect;
             config[ConfigKeyPrefix + "OnConnectCommands"] = OnConnectCommands;
         }
diff -Nru smuxi-1.1+master.bzr537~ubuntu20.10.1/src/Engine/Config/UserConfig.cs smuxi-1.1+master.bzr538~ubuntu20.10.1/src/Engine/Config/UserConfig.cs
--- smuxi-1.1+master.bzr537~ubuntu20.10.1/src/Engine/Config/UserConfig.cs	2021-06-04 08:02:47.000000000 +0000
+++ smuxi-1.1+master.bzr538~ubuntu20.10.1/src/Engine/Config/UserConfig.cs	2021-06-08 18:31:55.000000000 +0000
@@ -98,6 +98,11 @@
                 return obj;
             }
             set {
+#if LOG4NET
+                if (value == null) {
+                    _Logger.Error($"set_Item[{key}]: value is null");
+                }
+#endif
                 Set(key, value);
             }
         }