diff --git a/src/testdir/test_eval_stuff.vim b/src/testdir/test_eval_stuff.vim
index 0c1e75d..1fbb74b 100644
--- a/src/testdir/test_eval_stuff.vim
+++ b/src/testdir/test_eval_stuff.vim
@@ -165,7 +165,7 @@
 
   call assert_fails('echo a . b', 'E15:')
   call assert_fails('let a .= b', 'E985:')
-  call assert_fails('let vers = 1.2.3', 'E15:')
+  call assert_fails('let vers = 1.2.3', 'E488:')
 
   if has('float')
     let f = .5
diff --git a/src/testdir/test_let.vim b/src/testdir/test_let.vim
index 1b8f74b..c05a4cb 100644
--- a/src/testdir/test_let.vim
+++ b/src/testdir/test_let.vim
@@ -314,6 +314,7 @@
     let ch = test_null_channel()
     call assert_fails('let ch += 1', 'E734:')
   endif
+  call assert_fails('let name = "a" .. "b",', 'E488: Trailing characters: ,')
 
   " This test works only when the language is English
   if v:lang == "C" || v:lang =~ '^[Ee]n'
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index d7fb1df..974ca85 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -2340,7 +2340,7 @@
   CheckScriptFailure(['vim9script', "var x = {xxx: 1,"], 'E723:', 2)
   CheckDefAndScriptFailure2(["var x = {['a']: xxx}"], 'E1001:', 'E121:', 1)
   CheckDefAndScriptFailure(["var x = {a: 1, a: 2}"], 'E721:', 1)
-  CheckDefExecAndScriptFailure2(["var x = g:anint.member"], 'E715:', 'E15:', 1)
+  CheckDefExecAndScriptFailure2(["var x = g:anint.member"], 'E715:', 'E488:', 1)
   CheckDefExecAndScriptFailure(["var x = g:dict_empty.member"], 'E716:', 1)
 
   CheckDefExecAndScriptFailure(['var x: dict<number> = {a: 234, b: "1"}'], 'E1012:', 1)
@@ -3052,7 +3052,7 @@
 
   call CheckDefAndScriptFailure2(["var x = [notfound]"], "E1001:", 'E121:', 1)
 
-  call CheckDefAndScriptFailure2(["var X = () => 123)"], "E488:", 'E15:', 1)
+  call CheckDefAndScriptFailure(["var X = () => 123)"], 'E488:', 1)
   call CheckDefAndScriptFailure(["var x = 123->((x) => x + 5)"], "E107:", 1)
 
   call CheckDefAndScriptFailure(["var x = &notexist"], 'E113:', 1)
@@ -3070,7 +3070,7 @@
   call CheckDefExecAndScriptFailure(["var x = +g:alist"], 'E745:', 1)
   call CheckDefExecAndScriptFailure(["var x = +g:adict"], 'E728:', 1)
 
-  call CheckDefAndScriptFailure2(["var x = ''", "var y = x.memb"], 'E715:', 'E15:', 2)
+  call CheckDefAndScriptFailure2(["var x = ''", "var y = x.memb"], 'E715:', 'E488:', 2)
 
   call CheckDefAndScriptFailure2(["'yes'->", "Echo()"], 'E488: Trailing characters: ->', 'E260: Missing name after ->', 1)
 
@@ -3354,8 +3354,8 @@
 endfunc
 
 func Test_expr_fails()
-  call CheckDefAndScriptFailure2(["var x = '1'is2"], 'E488:', 'E15:', 1)
-  call CheckDefAndScriptFailure2(["var x = '1'isnot2"], 'E488:', 'E15:', 1)
+  call CheckDefAndScriptFailure(["var x = '1'is2"], 'E488:', 1)
+  call CheckDefAndScriptFailure(["var x = '1'isnot2"], 'E488:', 1)
 
   call CheckDefAndScriptFailure2(["CallMe ('yes')"], 'E476:', 'E492:', 1)
 
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 9237fdf..4b0ab2b 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -3212,7 +3212,7 @@
       'if 1# comment3',
       '  echo "yes"',
       'endif',
-      ], 'E15:')
+      ], 'E488:')
 
   CheckScriptFailure([
       'vim9script',
@@ -3221,7 +3221,7 @@
       'elseif 2#comment',
       '  echo "no"',
       'endif',
-      ], 'E15:')
+      ], 'E488:')
 
   CheckScriptSuccess([
       'vim9script',
@@ -3231,7 +3231,7 @@
   CheckScriptFailure([
       'vim9script',
       'var v = 1# comment6',
-      ], 'E15:')
+      ], 'E488:')
 
   CheckScriptSuccess([
       'vim9script',
diff --git a/src/testdir/test_viminfo.vim b/src/testdir/test_viminfo.vim
index e70fed8..0518b91 100644
--- a/src/testdir/test_viminfo.vim
+++ b/src/testdir/test_viminfo.vim
@@ -128,7 +128,7 @@
         \ "!GLOB_BLOB_4\tBLO\t0z12 ab",
         \ "!GLOB_LIST_1\tLIS\t1 2",
         \ "!GLOB_DICT_1\tDIC\t1 2"], 'Xviminfo')
-  call assert_fails('rv! Xviminfo', 'E15:')
+  call assert_fails('rv! Xviminfo', 'E488:')
   call assert_equal('123', g:GLOB_BLOB_1)
   call assert_equal(1, type(g:GLOB_BLOB_1))
   call assert_equal('012', g:GLOB_BLOB_2)
diff --git a/src/testdir/test_vimscript.vim b/src/testdir/test_vimscript.vim
index 89c1001..de87658 100644
--- a/src/testdir/test_vimscript.vim
+++ b/src/testdir/test_vimscript.vim
@@ -5570,7 +5570,7 @@
     call T(19, '{(1} + CONT(19)',	'E110',	"Missing ')'")
     call T(20, '("abc"[1) + CONT(20)',	'E111',	"Missing ']'")
     call T(21, '(1 +) + CONT(21)',	'E15',	"Invalid expression")
-    call T(22, '1 2 + CONT(22)',	'E15',	"Invalid expression")
+    call T(22, '1 2 + CONT(22)',	'E488',	"Trailing characters: 2 +")
     call T(23, '(1 ? 2) + CONT(23)',	'E109',	"Missing ':' after '?'")
     call T(24, '("abc) + CONT(24)',	'E114',	"Missing quote")
     call T(25, "('abc) + CONT(25)",	'E115',	"Missing quote")