diff --git a/share/functions/__fish_theme_freeze.fish b/share/functions/__fish_theme_freeze.fish
index 3bafda209..4b6b8355c 100644
--- a/share/functions/__fish_theme_freeze.fish
+++ b/share/functions/__fish_theme_freeze.fish
@@ -11,16 +11,18 @@ function __fish_theme_freeze
 
     printf >$__fish_config_dir/$relative_path %s\n \
         $(test $data_source = __fish_theme_migrate &&
-            echo '# This file was created by fish to migrate the default universal variables.') \
+            echo "\
+# This file was created by fish when upgrading to version 4.3, to migrate
+# theme variables from universal to global scope.") \
         "\
-# Don't edit this, as it will be written by the web-config tool (`fish_config`).
+# Don't edit this file, as it will be written by the web-config tool (`fish_config`).
 # To customize your theme, delete this file and see
 #     help $help_section
 # or
 #     man fish-interactive | less +/^SYNTAX.HIGHLIGHTING
 # for appropriate commands to add to ~/.config/fish/config.fish instead." \
         $(test $data_source = __fish_theme_migrate &&
-            echo '# See also the release notes for fish 4.3.0 (`help relnotes`).') \
+            echo '# See also the release notes for fish 4.3.0 (run `help relnotes`).') \
         "" \
         'set --global '$theme_data
 end
diff --git a/share/functions/__fish_theme_migrate.fish b/share/functions/__fish_theme_migrate.fish
index b900c0da1..a51eb4454 100644
--- a/share/functions/__fish_theme_migrate.fish
+++ b/share/functions/__fish_theme_migrate.fish
@@ -8,9 +8,11 @@ function __fish_theme_migrate
     end
 
     set -l removing_uvars false
+    set -l msg
     # Copy legacy uvars to globals.
     if set -l theme_uvars (__fish_theme_variables --universal)
         set removing_uvars true
+        set -l msg_suffix .
         if not __fish_config_theme_uvars_subset_of_historical_default $theme_uvars
             for varname in $theme_uvars
                 set -g $varname $$varname
@@ -20,11 +22,12 @@ function __fish_theme_migrate
                 set -a theme_data "$(string escape -- $varname $$varname | string join " ")"
             end
             __fish_theme_freeze __fish_theme_migrate $theme_data
-            echo -s (set_color --bold) 'fish:' (set_color normal)' color variables are no longer set in universal scope by default.'
-            echo "Migrated them to global variables set in $(set_color --underline)$(
+            set msg_suffix " by default."\n"  Migrated them to global variables set in $(set_color --underline)$(
                     __fish_unexpand_tilde $__fish_config_dir/conf.d/fish_frozen_theme.fish
                 )$(set_color normal)"
         end
+        set -a msg "* Color variables are no longer set in universal scope$msg_suffix"
+        set -a msg '  To restore syntax highlighting in other fish sessions, please restart them.'
     end
     if set -Uq fish_key_bindings
         set removing_uvars true
@@ -32,10 +35,10 @@ function __fish_theme_migrate
         set -l filename $__fish_config_dir/$relative_filename
         __fish_backup_config_files $relative_filename
         echo >$filename "\
-# This file was created by fish to migrate the 'fish_key_bindings' variable
-# from its old default scope (universal) to its new default scope (global).
-# It is recommended you delete this file and configure key bindings however
-# you prefer.
+# This file was created by fish when upgrading to version 4.3, to migrate
+# the 'fish_key_bindings' variable from its old default scope (universal)
+# to its new default scope (global).  We recommend you delete this file
+# and configure key bindings in ~/.config/fish/config.fish if needed.
 
 $(
     # No need to freeze the default value.
@@ -50,16 +53,19 @@ $(
 # whenever the fish_key_bindings variable is erased.
 # This means that as long as any fish < 4.3 is still running on this system,
 # we cannot complete the migration.
-# As a workaround, we erase the universal variable at every shell startup.
+# As a workaround, erase the universal variable at every shell startup.
 set --erase --universal fish_key_bindings"
-        echo -s (set_color --bold) 'fish:' (set_color normal) ' the fish_key_bindings variable is no longer set in universal scope by default.'
-        echo -s "Migrated it to a global variable set in  " \
+        set -a msg '* The fish_key_bindings variable is no longer set in universal scope by default.'
+        set -a msg (echo -s "  Migrated it to a global variable set in  " \
             "$(set_color --underline)$(__fish_unexpand_tilde $filename)" \
-            (set_color normal)
+            (set_color normal))
         source $__fish_config_dir/$relative_filename
     end
     set -U __fish_initialized 4300
     if $removing_uvars
+        echo -s (set_color --bold) 'fish:' (set_color normal) " upgraded to version 4.3:"
+        string join \n -- $msg
+        echo 'See also the release notes (type `help relnotes`).'
         set -Ue fish_key_bindings $theme_uvars
         set -l sh (__fish_posix_shell)
         eval "$sh -c 'sleep 7 # Please read above notice about universal variables' &"
diff --git a/tests/checks/__fish_theme_migrate.fish b/tests/checks/__fish_theme_migrate.fish
index 43a9146e5..93161bba8 100644
--- a/tests/checks/__fish_theme_migrate.fish
+++ b/tests/checks/__fish_theme_migrate.fish
@@ -31,10 +31,13 @@ echo no default universal variables
 
     provoke-migration
     $fish -c __fish_theme_migrate
-    # CHECK: {{\x1b\[1m}}fish:{{\x1b\[m}} {{.*}}
+    # CHECK: {{\x1b\[1m}}fish:{{\x1b\[m}} {{upgraded.*}}
+    # CHECK: {{.*Color.*no.longer.*universal.*}}
     # CHECK: Migrated {{.*}} {{\S*}}/xdg_config_home/fish/conf.d/fish_frozen_theme.fish{{\x1b\[m}}
-    # CHECK: {{\x1b\[1m}}fish:{{\x1b\[m}} {{.*}}
+    # CHECK: {{.*restart.*}}
+    # CHECK: {{.*fish_key_bindings.*no.longer.*universal.*}}
     # CHECK: Migrated {{.*}} {{\S*}}/xdg_config_home/fish/conf.d/fish_frozen_key_bindings.fish{{\x1b\[m}}
+    # CHECK: {{.*help relnotes.*}}
     grep -v '^#' $__fish_config_dir/conf.d/fish_frozen_theme.fish | grep . | head -3
     # CHECK: set --global fish_color_autosuggestion 7f7f7f
     # CHECK: set --global fish_color_cancel ffffff --background=000000
@@ -54,13 +57,17 @@ echo no default universal variables
     set -Ue fish_color_autosuggestion
 }
 
-# If existing universal variables match old defaults exactly (common case), pretend they don't
-# exist at all (silently delete them).
+# If existing universal colors match old defaults exactly (common case), don't migrate but
+# delete them.
 {
     echo yes | fish_config theme save default --color-theme=unknown
     fake-old-uvars
     provoke-migration
     $fish -c __fish_theme_migrate
+    # CHECK: {{\x1b\[1m}}fish:{{\x1b\[m}} {{upgraded.*}}
+    # CHECK: {{.*Color.*no.longer.*universal.*}}
+    # CHECK: {{.*restart.*}}
+    # CHECK: {{.*help relnotes.*}}
     not path is $__fish_config_dir/conf.d/fish_frozen_theme.fish
     and echo ok
     # CHECK: ok
@@ -86,14 +93,18 @@ echo no default universal variables
     '
 }
 
-# If existing universal variables match old defaults exactly (common case),
-# don't migrate them and silently delete them).
+# If existing universal key bindings match old defaults exactly (common case), don't migrate
+# but delete them).
 {
     set -U fish_key_bindings fish_vi_key_bindings
     provoke-migration
     $fish -c __fish_theme_migrate
-    # CHECK: {{\x1b\[1m}}fish:{{\x1b\[m}} {{.*}}.
+    # CHECK: {{\x1b\[1m}}fish:{{\x1b\[m}} {{upgraded.*}}
+    # CHECK: {{.*Color.*no.longer.*universal.*}}
+    # CHECK: {{.*restart.*}}
+    # CHECK: {{.*fish_key_bindings.*no.longer.*universal.*}}
     # CHECK: Migrated {{.*}} {{\S*}}/xdg_config_home/fish/conf.d/fish_frozen_key_bindings.fish{{\x1b\[m}}
+    # CHECK: {{.*help relnotes.*}}
     path is $__fish_config_dir/conf.d/fish_frozen_key_bindings.fish
     and echo ok
     # CHECK: ok