What does errno 81 (EBADFD) in Solaris mean?

EBADFD

Descriptor state mismatch

EBADFD is Solaris errno 81 (f.d. invalid for this operation). Solaris rejected an operation because the file descriptor is in a bad state for that request.

A descriptor number can still be open while being unusable for a particular request. Record the descriptor type, open flags, and the operation that last changed its state; blindly reopening it can hide the lifecycle error in the caller.

What to check

• Check whether the descriptor is open, its access mode, and whether the requested operation matches that mode.
• Oracle documents cases such as reading from a descriptor opened only for writing.
• Log descriptor lifecycle events to catch reuse after close.

References

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