How to distinguish permissions, ownership, filesystem flags, and OS protections behind this error.
Operation not permitted can look like a simple permission problem, but it can also come from immutable flags, system protections, mount options, sandboxing, or security policies that go beyond normal read/write bits.
Check ownership and permissions first, then look for filesystem flags, mount restrictions, or platform security protections such as SIP or container sandboxing.
Inspect the exact operation and path so you can narrow whether the block is from the filesystem, kernel policy, or higher-level sandboxing.
Do not assume root or sudo automatically bypasses every form of restriction.
Do not treat this exactly like a normal permission denied error without checking the wider environment.