Error when creating a new Blog category

1. Login with Admin or a normal user on XE 7.4.
2. Create a new Blog page.
3. When you`re in Edit mode, create a new Blog Category.

Actual result:

• Even you are with Admin, a normal user, even if you create a blog category or subcategory, after you complete the name of the category and click Add, you get a red error message on all the screen ( check the image attached )
• If I refresh the page, the error is gone and the category or subcategory was successfully created.

Expected result:

• I expect to create a blog category or subcategory without seeing the red error message on all the screen.