diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 7b03046301..deb41b2011 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -5439,11 +5439,19 @@ valid_custom_variable_name(const char *name)
 {
 	bool		saw_sep = false;
 	bool		name_start = true;
+	int 		placeholder_length = 0;
 
 	for (const char *p = name; *p; p++)
 	{
+		placeholder_length++;
 		if (*p == GUC_QUALIFIER_SEPARATOR)
 		{
+			/* Check invalid placeholder and custom parameter*/
+			char *placeholder = malloc(sizeof(char) * (placeholder_length - 1));
+			strncpy(placeholder, name, placeholder_length - 1);
+			placeholder[placeholder_length -1] = '\0';
+			EmitWarningsOnPlaceholders(placeholder);
+
 			if (name_start)
 				return false;	/* empty name component */
 			saw_sep = true;