robocopy exit codes: what 0, 1, 2, 3, 8 and 16 mean

Robocopy exit codes are not pass or fail. A code from 0 to 7 means the copy had no failure. A code of 8 or more means at least one failure.

What it means

Robocopy returns a number when it ends. Each bit of that number says something different, and bits can be added together. This is why you see codes like 3 or 7.

Microsoft’s note is short: any value equal to or greater than 8 indicates that there was at least one failure during the copy operation.

The bit table

Bit	Meaning if set
1	One or more files were copied successfully (new files arrived).
2	Extra files or directories exist in the destination that are not in the source.
4	Some files or directories are mismatched. Look at the log.
8	Some files or directories could not be copied. Copy errors happened and the retry limit was used up.
16	Serious error. Robocopy copied no files. Either a usage error, or not enough access on the source or destination.

Common codes

Code	What happened	Failure?
0	Nothing was copied. The files already exist in the destination, so the copy was skipped. No mismatch.	No
1	All files were copied successfully.	No
2	Extra files exist in the destination. Nothing was copied.	No
3	Some files were copied, and extra files exist (1 + 2).	No
4	Mismatched files or directories were found.	No
5	Some files were copied and some were mismatched (1 + 4).	No
6	Extra and mismatched files exist. Nothing was copied.	No
7	Files were copied, and there were mismatches and extra files (1 + 2 + 4).	No
8	Several files did not copy.	Yes
9 to 15	Bit 8 plus a mix of bits 1, 2 and 4. Some files failed, and the rest of the digits say what else happened.	Yes
16	Serious error. Nothing was copied.	Yes

Codes of 16 and above (16 plus other bits) also mean a serious error. A code above 7 always needs a look at the log.

How Devpit fixes or avoids it

Only Share Files runs robocopy. It copies big folders between two PCs with live progress, automatic retry and resume. It reads robocopy’s log, so it works in any Windows language. At the end it shows a clear “Done”, or a list of the files that failed with a reason for each, so you do not have to read exit codes. It uses /E /XJ /XO /MT:16 /Z /R:3 /W:5. /XO keeps a file that is newer on the receiving PC instead of overwriting it with an older copy, and it never uses /MIR or /PURGE, so nothing on the receiving PC is ever deleted.

The manual fix

1. Read the code robocopy left behind. In PowerShell:

$LASTEXITCODE

2. Write a log so you can read what happened. /LOG: writes the status to a file, and /TEE also shows it on screen:

robocopy C:\src D:\dst /E /LOG:C:\copy.log /TEE

3. If the code is 8 or more, open the log and search for ERROR. Fix the named files or folders and run the same command again. Robocopy skips files that are already the same.
4. For unreliable networks, /Z copies in restartable mode, so an interrupted file can pick up where it left off. /R:n sets how many times to retry a failed copy (the default is 1,000,000) and /W:n sets the wait between retries in seconds (the default is 30):

robocopy C:\src \\pc2\share /E /Z /R:5 /W:10

5. In a script, test for failure with a code of 8 or more, not for non-zero.

Sources

• Microsoft: robocopy (options and exit codes)
• Microsoft: Return codes used by the Robocopy utility
• SS64: Robocopy exit codes (bit values 1, 2, 4, 8 and 16)
• Microsoft: about_Automatic_Variables ($LASTEXITCODE)