There is no longer support for 8 bit color depth in TigerVNC (see:
https://github.com/TigerVNC/tigervnc/commit/e86d8720ba1e79b486ca29a5c2b27fa25811e6a2);
using it causes a fatal error.

Submitted upstream at: https://github.com/canonical/lightdm/pull/265.

diff --git a/data/lightdm.conf b/data/lightdm.conf
index 0df38429..60e3e8b4 100644
--- a/data/lightdm.conf
+++ b/data/lightdm.conf
@@ -160,4 +160,4 @@
 #listen-address=
 #width=1024
 #height=768
-#depth=8
+#depth=24
diff --git a/src/x-server-xvnc.c b/src/x-server-xvnc.c
index 68340d53..27ca4454 100644
--- a/src/x-server-xvnc.c
+++ b/src/x-server-xvnc.c
@@ -127,7 +127,7 @@ x_server_xvnc_init (XServerXVNC *server)
     XServerXVNCPrivate *priv = x_server_xvnc_get_instance_private (server);
     priv->width = 1024;
     priv->height = 768;
-    priv->depth = 8;
+    priv->depth = 24;
 }
 
 static void
diff --git a/tests/scripts/vnc-command.conf b/tests/scripts/vnc-command.conf
index 0f1e25fd..335956d9 100644
--- a/tests/scripts/vnc-command.conf
+++ b/tests/scripts/vnc-command.conf
@@ -19,7 +19,7 @@ command=Xvnc -option
 #?VNC-CLIENT CONNECT
 
 # Xvnc server starts
-#?XVNC-0 START GEOMETRY=1024x768 DEPTH=8 OPTION=TRUE
+#?XVNC-0 START GEOMETRY=1024x768 DEPTH=24 OPTION=TRUE
 
 # Daemon connects when X server is ready
 #?*XVNC-0 INDICATE-READY
diff --git a/tests/scripts/vnc-guest.conf b/tests/scripts/vnc-guest.conf
index 431bb244..ce2b97db 100644
--- a/tests/scripts/vnc-guest.conf
+++ b/tests/scripts/vnc-guest.conf
@@ -21,7 +21,7 @@ user-session=default
 #?VNC-CLIENT CONNECT
 
 # Xvnc server starts
-#?XVNC-0 START GEOMETRY=1024x768 DEPTH=8 OPTION=FALSE
+#?XVNC-0 START GEOMETRY=1024x768 DEPTH=24 OPTION=FALSE
 
 # Daemon connects when X server is ready
 #?*XVNC-0 INDICATE-READY
diff --git a/tests/scripts/vnc-login.conf b/tests/scripts/vnc-login.conf
index cdfe17b8..f0d65b7f 100644
--- a/tests/scripts/vnc-login.conf
+++ b/tests/scripts/vnc-login.conf
@@ -21,7 +21,7 @@ user-session=default
 #?VNC-CLIENT CONNECT
 
 # Xvnc server starts
-#?XVNC-0 START GEOMETRY=1024x768 DEPTH=8 OPTION=FALSE
+#?XVNC-0 START GEOMETRY=1024x768 DEPTH=24 OPTION=FALSE
 
 # Daemon connects when X server is ready
 #?*XVNC-0 INDICATE-READY
diff --git a/tests/scripts/vnc-open-file-descriptors.conf b/tests/scripts/vnc-open-file-descriptors.conf
index 753c84dd..e5d35730 100644
--- a/tests/scripts/vnc-open-file-descriptors.conf
+++ b/tests/scripts/vnc-open-file-descriptors.conf
@@ -21,7 +21,7 @@ user-session=default
 #?VNC-CLIENT CONNECT
 
 # Xvnc server starts
-#?XVNC-0 START GEOMETRY=1024x768 DEPTH=8 OPTION=FALSE
+#?XVNC-0 START GEOMETRY=1024x768 DEPTH=24 OPTION=FALSE
 
 # Daemon connects when X server is ready
 #?*XVNC-0 INDICATE-READY
<span title='2022-12-04 22:25:23 +0100'>2022-12-04</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=2e75b328b6bbdadbffe5b643a4891b5026a0defd'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>po/packages/vi.po: New file.
po/packages/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-11-04 10:56:38 +0100'>2022-11-04</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=a65ce9dd500460af4f97e7398fb35dd817f4c677'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* po/guix/lt.po: New file.
* po/guix/LINGUAS: Add lt.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-09-04 16:52:02 +0200'>2022-09-04</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=77e3042aef6d8e519d016555464e466399318b4f'>nls: Update translations.</a></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-07-09 21:49:34 +0200'>2022-07-09</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=e0d47d8facafb6d6c04741bbf30eefbc68aaefb9'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>po/guix/tr.po: New file.
po/guix/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-06-04 17:42:54 +0200'>2022-06-04</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=809c57c872a6dd48007d1abf6d7f3dd1482ec53a'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>po/packages/tr.po: New file.
po/packages/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-05-01 18:07:34 +0200'>2022-05-01</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=6b4124cdcc203d47dc40158062afa1497d73d592'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>po/guix/ja.po: New file.
po/guix/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-04-02 18:42:36 +0200'>2022-04-02</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=8a208df17fe81fbf34f5a86cc52bb0b8e33c7b96'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* po/packages/fi.po: New file.
* po/packages/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-02-04 18:29:00 +0100'>2022-02-04</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=8391a99d089322a39cbacb1e6dc2979d8b2ef7c9'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* po/doc/guix-cookbook.pt_BR.po: New file.
* po/doc/local.mk: Add it.
* doc/local.mk: Add pt_BR cookbook.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-01-09 11:35:59 +0100'>2022-01-09</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=934b0cdfee2078bad42429427e12d6ee2ddb7fec'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* po/doc/guix-cookbook.fi.po: New file.
* po/doc/guix-manual.fi.po: New file.
* po/doc/local.mk: Add them.
* doc/local.mk: Add them.
* po/guix/fi.po: New file.
* po/guix/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2021-10-17 22:10:25 +0200'>2021-10-17</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=15c91189cb61c579f4289047c79530cefe75215f'>nls: Update translations.</a></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2021-09-02 04:06:52 +0200'>2021-09-02</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=1ff2092a39dc5c7c7cd9b4a0ba4b59f92e738efc'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* po/packages/it.po: New file.
* po/packages/LINGUAS: Add `it'.
* po/*/*.po: Update translations.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2021-08-04 14:49:53 +0200'>2021-08-04</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=6c10c96fedf707d7be059aeb79bd5c8e2d2fa210'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* po/doc/guix-cookbook.ru.po: New file.
* po/doc/guix-cookbook.sk.po: New file.
* po/*/*.po: Update translations.
* doc/local.mk (COOKBOOK_LANGUAGES): Add ru and sk.
(info_TEXINFOS): Add Russian and Slovak cookbooks.
* po/doc/local.mk (DOC_COOKBOOK_PO_FILES): Add Russian and Slovak po
files.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2021-05-10 22:34:43 -0400'>2021-05-10</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=21fcced608c93e1ac836cdd9ab8c5d200c667e75'>nls: Update translations.</a></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2021-04-18 13:17:31 +0200'>2021-04-18</span></td><td><a href='/guix/commit/po/doc/guix-cookbook.fr.po?id=58c5911652cfda308d45c190bad3e79367b1d200'>nls: Add French translation of the cookbook.</a></td><td>Julien Lepiller</td></tr>