Check Out failed. Message "Operation failed because it requires both read and write privileges"

The files with the problem reported originated from the project that had some security access restrictions set.

Some time ago these security restrictions were lifted on all the projects, but the files that became members of the derived (subsequent) projects retained these restrictions.

If these restrictions are no longer relevant - ask an admin or a member of original security group to remove them, by checking out files and changing the security on each file individually,
if they still are - see if you should be the member of the group that does have the write access to these files.

To remove files access restrictions:
- create a task and check out the file(s),

- right click the file object,

- select Properties -> Security.

- see the groups managing the object,
- remove the check mark by the group name or check the appropriate radio button to remove the restrictions altogether,
- complete task.