diff --git a/x-pack/plugins/index_management/common/constants/invalid_characters.ts b/x-pack/plugins/index_management/common/constants/invalid_characters.ts
index 311de74f54733..e3a66477d71ae 100644
--- a/x-pack/plugins/index_management/common/constants/invalid_characters.ts
+++ b/x-pack/plugins/index_management/common/constants/invalid_characters.ts
@@ -7,4 +7,4 @@
 
 export const INVALID_INDEX_PATTERN_CHARS = ['\\', '/', '?', '"', '<', '>', '|'];
 
-export const INVALID_TEMPLATE_NAME_CHARS = ['"', '*', '\\', ',', '?'];
+export const INVALID_TEMPLATE_NAME_CHARS = ['"', '*', '\\', ',', '?', '#'];