Changing permissions via chmod at runtime errors with "Operation not permitted"

It sounds like you are trying to use the chmod command to change the permissions on a file, but you are encountering an error that says "Operation not permitted". There could be a few reasons for this.

One reason could be that you do not have sufficient permissions to modify the file's permissions. In order to change the permissions on a file, you need to be the owner of the file, or you need to have superuser privileges (e.g., by using sudo).

Another possibility is that the file has an immutable attribute set on it. The immutable attribute is a file system flag that prevents a file from being modified or deleted. This attribute can be set using the chattr command, and it can only be removed by a user with superuser privileges.

Finally, it's also possible that you are encountering this error because of some other system restriction, such as a security policy or a filesystem mount option. In this case, you may need to speak with your system administrator to understand the cause of the error and how to resolve it.