Errors

PowerShell features a built-in automatic variable called $Error, which acts as a global history log for all errors occurring during your current session.

Additionally, PowerShell provides a built-in common parameter called -ErrorVariable, allowing you to capture command-specific errors into a custom variable.

The Global $Error Variable

The $Error variable is a built-in, system-managed collection (ArrayList) containing ErrorRecord objects.

• Reverse Order: The most recent error is always stored at index 0 ($Error[0]).
• Session Bound: The array is ephemeral and clears automatically when you close the PowerShell session.
• Inspection: You can access specific error details like exception messages or stack traces using dot notation.

# View the most recent error object
\$Error[0]
 
# View the deep technical details of the latest error
\$Error[0] | Select-Object *
 
# Check how many errors have occurred in this session
\$Error.Count
 
# Clear the error history log completely
\$Error.Clear()

The -ErrorVariable Parameter (and -EV)

Every built-in PowerShell cmdlet supports the -ErrorVariable parameter. This isolates and intercepts errors from a single command without forcing you to parse the entire global $Error collection.

• No Dollar Sign: When defining the variable inside the parameter, pass the name without the $ prefix.
• Overwrite Default: By default, running a new command overwrites your custom error variable.
• Appending (+): Prepend a + sign to the variable name to add new errors to the existing collection instead of wiping it out.

# Capture errors into a variable named MyErrors (No \$ used in the parameter)
Get-ChildItem -Path "C:\NonExistentFolder" -ErrorVariable MyErrors
 
# Read the captured error (Use \(here to read it)\)MyErrors
 
# Silently suppress console errors but still log them to a variable
Get-Service -Name "FakeService" -ErrorVariable ServiceErr -ErrorAction SilentlyContinue
\$ServiceErr
 
# Append errors across multiple distinct commands using "+"
Get-Item "C:\MissingFile1.txt" -ErrorVariable +BatchErrors -ErrorAction SilentlyContinue
Get-Item "C:\MissingFile2.txt" -ErrorVariable +BatchErrors -ErrorAction SilentlyContinue
\$BatchErrors.Count # Returns 2

Other Built-In Error Elements