Forum Discussion
File copy speed drops to zero and stays there mid-transfer
Whenever I copy large files between drives, the speed starts off fine—then randomly drops to 0 MB/s and just sits there. Sometimes it resumes after a minute, sometimes it never does and I have to cancel and restart.
I've already checked the drive health with built-in tools, tried different USB ports and cables, and disabled antivirus temporarily. Nothing changed. It's an SSD and an external HDD, both showing no errors.
Anyone run into this or know what's causing it?
1 Reply
A zero-speed display does not distinguish a slow operation from an I/O failure, and a clean filesystem check does not identify every possible storage problem. Since you already tested cables and ports, preserve the original files and capture a controlled transfer result. For one test file, run robocopy "SOURCE" "NEW-DESTINATION" "FILENAME" /J /R:1 /W:2 /LOG:copy-test.log, replacing the placeholders. This uses unbuffered copying, limits retries, and records errors. Do not use /MOVE, /MIR, or /PURGE for this test. Compare the same file in the opposite direction, then with another destination if available. Check Event Viewer around the stall for disk, filesystem, or storage-controller errors. Re-enable antivirus, since disabling it did not change the behavior. If the transfer reports an error, share its exact code, direction, drive models, and connection type; that is stronger evidence than assuming the progress bar proves a particular cause.
