What does errno 48 (ENOTSUP) in Solaris mean?

ENOTSUP

Unsupported feature or operation

ENOTSUP is Solaris errno 48 (Operation not supported). Solaris does not support the requested feature or operation in this system version or object context.

Separate a platform capability limit from a bad argument. Record the object type, filesystem or device, operation flags, and Solaris version so a supported fallback can be chosen without repeatedly issuing an operation the object cannot implement.

What to check

• Check whether the failure is system-wide support, filesystem support, socket option support, or device capability.
• Use feature detection and alternate code paths rather than retry loops.
• Do not assume it means invalid syntax; EINVAL is a different contract violation.

References

• Oracle Solaris intro(2): error numbers
• illumos errno.h definitions
• POSIX errno.h