What it means Output current went over the drive's overcurrent level.
Likely causes
Short
Jam
Accel too fast
Wrong V/f
Checks, in order
Megger
Check accel
Check mechanics
Source
Source (reworded, not copied): Yaskawa, GA500 Drive Maintenance & Troubleshooting Manual, TOEPYAIGA5001A, Faults. Official manual (PDF). Fault numbers and names can differ between firmware versions.