When you’re creating columns either the Site Columns or the List Columns in SharePoint, suddenly it might show a message stating “The column name that you entered is already in use or reserved. Choose another name.”.
When this error comes, you normally go to the create new column page and try to add the same content type again. But the added column will not be shown in the column list. To display this column in the content type column list, just run the following script.
Copy the above script and paste it in the browser URL and then press enter. You will get a confirmation message box as shown below.
After clicking OK, when you go again to the content type columns page, the column will become visible.
When this error comes, you normally go to the create new column page and try to add the same content type again. But the added column will not be shown in the column list. To display this column in the content type column list, just run the following script.
javascript:g_FieldName={};alert(
'Successfully cleared forbidden columns'
);
Copy the above script and paste it in the browser URL and then press enter. You will get a confirmation message box as shown below.
After clicking OK, when you go again to the content type columns page, the column will become visible.