Power Automate provides various functions for data manipulation, logic evaluation, and formatting. However, using the wrong number of arguments in a function can lead to an error message like:
“Function arguments mismatch – The number of arguments passed to a function doesn’t match the required ones.”
This error occurs when:
- Too many or too few parameters are passed to a function.
- A function requires optional arguments, but they are missing.
- The wrong data type is used, affecting argument count.
- Function syntax is incorrect, leading Power Automate to misinterpret arguments.
2. Common Causes of “Function Arguments Mismatch” Error
| Cause | Description | Example |
|---|---|---|
| Missing Required Arguments | A function needs a certain number of parameters, but fewer were provided. | substring('Power Automate', 5) (missing length argument) |
| Too Many Arguments | Extra parameters are passed that the function does not expect. | add(5, 10, 15) (only accepts two) |
| Wrong Data Type Affecting Arguments | A function expects specific data types, but an incorrect one was provided. | add('five', 5) (expects numbers) |
| Incorrect Parameter Order | Some functions require arguments in a specific order. | split(',', 'Power Automate') (should be split('Power Automate', ',')) |
3. Step-by-Step Troubleshooting Guide
Step 1: Identify the Function Causing the Error
- Go to Power Automate (https://flow.microsoft.com).
- Open My Flows and find the flow that failed.
- Click Run History and locate the failed execution.
- Expand the failed action and check the error message.
Example Error Message:
"The function 'substring' expects 3 arguments but received 2."
Step 2: Verify the Required Number of Arguments
Each Power Automate function expects a fixed number of arguments. Ensure you are passing the correct amount.
Solution: Check the official documentation or use the Expression Builder to verify function requirements.
Example Fix:
| Function | Required Arguments | Correct Example |
|---|---|---|
substring() | 3 (text, startIndex, length) | substring('Power Automate', 0, 5) |
add() | 2 (number1, number2) | add(5, 10) |
replace() | 3 (text, oldText, newText) | replace('Power Automate', 'Power', 'Flow') |
split() | 2 (text, separator) | split('Power Automate', ' ') |
Incorrect (substring() missing third argument):
substring('Power Automate', 5)
The function expects 3 arguments, but only 2 were provided.
Correct:
substring('Power Automate', 5, 3)
Step 3: Remove Extra Arguments if Needed
Some functions only accept a specific number of parameters, and providing more will cause an error.
Solution: Remove the extra argument.
Example Fix:
Incorrect (add() with extra argument):
add(5, 10, 15)
add() only accepts two numbers.
Correct:
add(5, 10)
Step 4: Ensure Correct Data Type for Each Argument
Sometimes, a function expects numbers but receives text, causing an argument count issue.
Solution: Convert data types using int(), string(), or float().
Example Fix:
Incorrect (add() expects numbers, but text is provided):
add('five', 5)
Power Automate does not automatically convert "five" to a number.
Correct:
add(int('5'), 5)
Step 5: Verify the Order of Parameters
Some functions require parameters in a specific order. If they are swapped, Power Automate may treat them incorrectly.
Solution: Reorder arguments properly.
Example Fix:
Incorrect (split() with wrong order):
split(',', 'Power Automate')
The text to split must come first, then the separator.
Correct:
split('Power Automate', ',')
Step 6: Test the Fixed Expression in Power Automate
Before running the flow, test the corrected expression:
- Open the Expression Builder.
- Copy the corrected function into a Compose action.
- Click Test and check the output.
If the output is incorrect, adjust the expression based on the troubleshooting steps above.
4. Preventative Measures
✔ Check the official documentation for function syntax before using it.
✔ Use Power Automate’s Expression Builder to validate functions before running a flow.
✔ Ensure the correct number of arguments are provided for each function.
✔ Convert data types if necessary to prevent argument mismatches.
✔ Test expressions in a “Compose” action before integrating them into a flow.