Expression execution failed – A formula or expression failed to execute during the flow.

Power Automate allows users to create expressions for manipulating and transforming data. However, during execution, some expressions may fail due to errors in syntax, missing data, or unsupported operations.

If an expression fails to execute, you might see the following error:

“Expression execution failed – A formula or expression failed to execute during the flow.”

This error occurs when:

• The syntax of the expression is incorrect.
• The expression references missing or null data.
• The data type does not match the expected input.
• Functions are used incorrectly or in the wrong context.
• Mathematical operations involve invalid values (e.g., division by zero).

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2. Common Causes of Expression Execution Failure

Cause	Description	Example
Syntax Errors	Incorrect function format, missing commas, or incorrect brackets.	concat('Hello' 'World') (missing comma)
Null or Missing Data	The field being referenced is empty or missing.	length(body('Get_item')?['Title']) when Title is null.
Incorrect Data Type	The function expects a different type (e.g., passing text to a number function).	add('text', 5) (cannot add text and number).
Incorrect Context Usage	Using functions in actions that do not support them.	items('Get_items')?['Title'] outside of a loop.
Division by Zero	A calculation tries to divide by zero, which is undefined.	div(10, 0).
Invalid Function Usage	Using an unsupported or unavailable function.	LEFT('Power Automate', 5) (Excel function, not Power Automate).

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3. Step-by-Step Troubleshooting Guide

Step 1: Identify the Failing Expression

1. Go to Power Automate (https://flow.microsoft.com).
2. Open My Flows and select the flow with the error.
3. Click Run History and find the failed execution.
4. Expand the failed action and look for the expression error message.

✔ Example Error Message:

"InvalidTemplate. Unable to process template language expressions in action 'Compose' inputs at line 1 and column 5: The function 'add' was unable to process input parameters."

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Step 2: Fix Syntax Errors

Expressions must follow correct Power Automate syntax, including:

• Using proper function formats (e.g., concat('Hello', ' World') instead of concat('Hello' 'World')).
• Ensuring correct spacing and commas.
• Using double quotes (") or single quotes (') consistently for strings.

Solution: Ensure correct syntax formatting.

Example Fix:
Incorrect:

concat('Hello' 'World')

Correct:

concat('Hello', ' World')

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Step 3: Handle Null or Missing Data

If an expression references missing or null data, it will fail.

Solution: Use the coalesce() function to provide a default value.

Example Fix:
Incorrect:

length(body('Get_item')?['Title'])

Correct:

length(coalesce(body('Get_item')?['Title'], ''))

This prevents the error when Title is null.

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Step 4: Ensure Correct Data Types

Some functions require specific data types (e.g., numbers for math functions).

✅ Solution: Convert data types using int(), string(), or float().

Example Fix:
Incorrect (trying to add a string and number):

add('5', 10)

Correct (convert string to number first):

add(int('5'), 10)

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Step 5: Ensure Functions Are Used in the Right Context

Certain functions should only be used inside loops or in specific actions.

Solution: Ensure the function is in the correct scope.

Example Fix:
Incorrect (using items() outside of a loop):

items('Get_items')?['Title']

Correct (inside an “Apply to Each” loop):

items('Apply_to_each')?['Title']

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Step 6: Prevent Division by Zero

If an expression attempts to divide by zero, Power Automate will return an error.

Solution: Check the divisor before performing division.

Example Fix:
Incorrect:

div(10, 0)

Correct:

if(equals(0, variables('divisor')), 'Cannot divide by zero', div(10, variables('divisor')))

This checks if the divisor is zero before performing division.

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Step 7: Validate Function Usage

Some functions from Excel, SQL, or JavaScript are not supported in Power Automate.

Solution: Use Power Automate equivalents.

Example Fix:

Unsupported Function (Excel/SQL)	Power Automate Equivalent
LEFT('text', 3)	substring('text', 0, 3)
RIGHT('text', 3)	substring('text', length('text') - 3, 3)
IF(A1>10, 'Yes', 'No')	if(greater(A1, 10), 'Yes', 'No')

Incorrect:

LEFT('Power Automate', 5)

Correct:

substring('Power Automate', 0, 5)

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Step 8: Test the Expression in Power Automate’s Expression Builder

Before running the flow, test the expression:

1. Open the Expression Builder.
2. Copy the expression into the field.
3. Click Test to see the output.

If an error appears, modify the expression based on the troubleshooting steps above.