diff --git a/src/tools/msvc/Solution.pm b/src/tools/msvc/Solution.pm
index 06893ee0ebc..353bcf50aa9 100644
--- a/src/tools/msvc/Solution.pm
+++ b/src/tools/msvc/Solution.pm
@@ -90,6 +90,7 @@ sub DeterminePlatform
 sub IsNewer
 {
 	my ($newfile, $oldfile) = @_;
+	-e $oldfile or warn "source file \"$oldfile\" does not exist";
 	if (   $oldfile ne 'src\tools\msvc\config.pl'
 		&& $oldfile ne 'src\tools\msvc\config_default.pl')
 	{
@@ -308,7 +309,7 @@ s{PG_VERSION_STR "[^"]+"}{__STRINGIFY(x) #x\n#define __STRINGIFY2(z) __STRINGIFY
 	if ($self->{options}->{python}
 		&& IsNewer(
 			'src\pl\plpython\spiexceptions.h',
-			'src\include\backend\errcodes.txt'))
+			'src\backend\utils\errcodes.txt'))
 	{
 		print "Generating spiexceptions.h...\n";
 		system(