Mac Error -50 — Parameter Error (paramErr)

Mac error -50 is a parameter error occurring during file operations on external drives, typically caused by file system incompatibility or corrupted metadata. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: Error -50 maps to paramErr — an invalid parameter was passed to a file system operation. Very common when writing to NTFS drives (macOS has read-only NTFS support). Also occurs with corrupted file metadata on HFS+ or APFS volumes. Can appear when ejecting drives that have pending write operations. Network shares with permission mismatches may trigger this error. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: Trying to write to an NTFS-formatted drive (read-only on macOS by default). Corrupted file system metadata on the target volume. File size exceeding FAT32 4GB limit when copying large files. PRAM/NVRAM storing outdated disk parameters. Corrupted preference files affecting file operations. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Check the drive format: Disk Utility > select drive > check Format column. For NTFS drives: use exFAT format instead (compatible with both Mac and Windows). Reset NVRAM: restart and hold Option+Command+P+R for 20 seconds. Run First Aid on the volume in Disk Utility. For network shares: disconnect and reconnect, verify credentials and permissions. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our Mac Error Codes collection on Error Codes Wiki. We provide comprehensive, up-to-date information to help you find solutions quickly.