Fix ERROR_INVALID_COMMAND_LINE (0x00000667) Fast

What's the Error?

You're seeing 0x00000667 — ERROR_INVALID_COMMAND_LINE. Windows can't make sense of the command string you passed. The culprit here is almost always a formatting issue: a missing closing quote, an unescaped special character (like &, ^, |), or a stray space where it shouldn't be.

I've seen this pop up most often in:

• Batch files with START or CALL commands that have paths with spaces
• PowerShell scripts passing arguments to legacy EXEs
• Scheduled tasks where the command line gets mangled by the task scheduler
• Custom installer scripts that don't quote paths properly

Let's work through it. Start with the simplest fix — you might be done in 30 seconds.

Fix 1: The 30-Second Check — Quoting

Look at the exact command line that triggers the error. If any path contains spaces, it must be enclosed in double quotes. Don't bother checking other stuff first — this is the cause 80% of the time.

Wrong:

C:\Program Files\MyApp\app.exe --config C:\My Config\settings.ini

Right:

"C:\Program Files\MyApp\app.exe" --config "C:\My Config\settings.ini"

If you're running this in a batch file, also check that you haven't accidentally split a quoted string across lines with the caret (^) line continuation. That will break the quote pairing.

Fix 2: The 5-Minute Fix — Escape Special Characters

If quoting the paths didn't fix it, you've got a special character that cmd.exe is eating. Characters like &, |, <, >, ^, %, and ! have special meaning in the shell and need to be escaped.

In cmd.exe (batch file or command prompt):

• Escape with ^ before the character. Example: echo This is ^& that
• Or wrap the whole thing in double quotes if the character is inside an argument: exe --name "Value & Co"

In PowerShell:

• Use backtick ` to escape. Example: --name "Value `& Co"
• Or use single quotes to prevent expansion: --name 'Value & Co'

Also check for trailing spaces in the command line. A space after a quoted string can break things, especially in scheduled tasks.

Fix 3: The Advanced Fix (15+ Minutes) — Rebuild the Command Line

If you're still stuck, the error is likely in how the command line is being constructed by another program or script. Here's the approach:

Step 1: Log the exact command line

Create a simple batch file called debug.cmd that just echoes its arguments:

@echo off
echo Arguments:
for %%a in (%*) do echo [%%a]

Replace your failing command with a call to debug.cmd and the same arguments. This shows you exactly what the shell is passing.

Step 2: Check for Unicode or non-ASCII characters

Sometimes copy-pasting from a web page or document brings in smart quotes (“ ”) instead of straight quotes (" "). Manually retype the command line in Notepad++ or a plain text editor to strip hidden formatting.

Step 3: Test with a minimal repro

Isolate the failing program. Run it with a single argument like --help or /?. If that works, add back arguments one by one until the error returns. Now you know which argument is the problem.

Step 4: Check the calling script or scheduler

If the command works in a manual command prompt but fails when run from a scheduled task or another script, the issue is in the invoker. Common culprits:

• Scheduled tasks: The "Start in (optional)" field can add unexpected path prefixing.
• Batch files: Using CALL with an EXE that has spaces in its path needs double quotes around the whole thing: CALL "C:\Path With Spaces\app.exe"
• PowerShell: Using Start-Process with -ArgumentList — you need to pass arguments as a string array, not a single quoted string. Example:

Start-Process -FilePath "C:\Program Files\MyApp\app.exe" -ArgumentList @("--config", "C:\My Config\settings.ini")

Step 5: Long path prefix

If the full command line exceeds 8191 characters (Windows limit for command line), you'll get this error. Shorten paths, use environment variables, or switch to a response file. Use dir /s /b on the path to check its length.

Prevention Tips

• Always quote paths with spaces. Gets you 90% of the way there.
• Avoid special characters in file names and paths if you can help it. Rename folders to remove &, +, etc.
• Use SETLOCAL ENABLEDELAYEDEXPANSION in batch files if you're manipulating strings with ! characters.
• Test complex commands in a command prompt before baking them into scripts.

That's it. Most people stop after Fix 1. If you're still hitting this after Fix 3, the problem is likely in the program's own argument parser — try contacting the vendor or checking their documentation for any special quoting rules.