AWS
DynamoDBValidationException - DynamoDB Validation Exception
Getting a **DynamoDBValidationException** means your DynamoDB request input doesn't satisfy DynamoDB constraints—attribute names, types, or expression syntax are invalid. This client-side error (4xx) happens when AWS validates DynamoDB request parameters. Most common when invalid attribute names are used in expressions, but also appears when expression syntax is invalid, attribute types don't match schema, reserved words are used as attribute names, or key schemas are invalid.
#Common Causes
- →Identity: IAM policy allows DynamoDB operations but validation fails. Service Control Policy (SCP) enforces validation rules.
- →Network: VPC endpoint DynamoDB validation restrictions. Request format invalid.
- →Limits: Invalid attribute name in expression. Invalid expression syntax. Type mismatch in expression. Reserved word used as attribute name. Invalid key schema.
✓Solutions
- 1Step 1: Diagnose - Check exact error message: AWS usually specifies which validation failed. Review error message for attribute name or expression. Check expression syntax.
- 2Step 2: Diagnose - Verify attribute names: Check if using reserved words (status, timestamp, etc.). Verify attribute names match table schema. Check if ExpressionAttributeNames is needed.
- 3Step 3: Diagnose - Check expression syntax: Verify UpdateExpression syntax (SET, REMOVE, ADD, DELETE). Check ConditionExpression syntax. Verify FilterExpression syntax.
- 4Step 4: Fix - Use ExpressionAttributeNames for reserved words: Use #status instead of status in expressions. Define in ExpressionAttributeNames: {"#status":"status"}. Use ExpressionAttributeValues for values: {":status":"active"}.
- 5Step 5: Fix - Verify attribute types match schema: Check table schema: aws dynamodb describe-table --table-name TABLE_NAME --query 'Table.AttributeDefinitions' --output json. Ensure attribute types match (S, N, B, SS, NS, BS).
</>Code Examples
Use ExpressionAttributeNames for Reserved Words
1#!/bin/bash
2TABLE_NAME="my-table"
3ITEM_KEY='{"id":{"S":"123"}}'
4
5echo "=== DynamoDB Update with ExpressionAttributeNames ==="
6echo "Using #status instead of 'status' (reserved word)"
7
8# Update with ExpressionAttributeNames
9aws dynamodb update-item \
10 --table-name ${TABLE_NAME} \
11 --key ${ITEM_KEY} \
12 --update-expression "SET #status = :status, #timestamp = :timestamp" \
13 --expression-attribute-names '{
14 "#status": "status",
15 "#timestamp": "timestamp"
16 }' \
17 --expression-attribute-values '{
18 ":status": {"S": "active"},
19 ":timestamp": {"S": "2024-01-01T00:00:00Z"}
20 }' \
21 --return-values ALL_NEW 2>&1
22
23if [ $? -eq 0 ]; then
24 echo "✓ Update successful"
25else
26 echo "✗ Update failed (DynamoDBValidationException)"
27 echo "Check expression syntax and attribute names"
28fiCheck Table Schema for Attribute Types
1#!/bin/bash
2TABLE_NAME="my-table"
3
4echo "=== Table Schema ==="
5aws dynamodb describe-table \
6 --table-name ${TABLE_NAME} \
7 --query 'Table.AttributeDefinitions' \
8 --output json
9
10echo "\n=== Key Schema ==="
11aws dynamodb describe-table \
12 --table-name ${TABLE_NAME} \
13 --query 'Table.KeySchema' \
14 --output json
15
16echo "\n=== Valid Attribute Types ==="
17echo "S: String"
18echo "N: Number"
19echo "B: Binary"
20echo "SS: String Set"
21echo "NS: Number Set"
22echo "BS: Binary Set"
23
24echo "\n=== Verify Attribute Types Match ==="
25echo "When updating items, ensure attribute types match schema"Validate UpdateExpression Syntax
1#!/bin/bash
2UPDATE_EXPRESSION="SET #status = :status"
3
4echo "=== Validating UpdateExpression Syntax ==="
5echo "Expression: ${UPDATE_EXPRESSION}"
6
7# Check for valid actions: SET, REMOVE, ADD, DELETE
8VALID_ACTIONS=("SET" "REMOVE" "ADD" "DELETE")
9FIRST_WORD=$(echo ${UPDATE_EXPRESSION} | cut -d' ' -f1)
10
11if [[ " ${VALID_ACTIONS[@]} " =~ " ${FIRST_WORD} " ]]; then
12 echo "✓ Valid action: ${FIRST_WORD}"
13else
14 echo "✗ Invalid action: ${FIRST_WORD}"
15 echo "Valid actions: ${VALID_ACTIONS[*]}"
16fi
17
18echo "\n=== Common Syntax Errors ==="
19echo "1. Missing action keyword (SET, REMOVE, ADD, DELETE)"
20echo "2. Missing ExpressionAttributeNames for reserved words"
21echo "3. Missing ExpressionAttributeValues for placeholders"
22echo "4. Invalid attribute type in ExpressionAttributeValues"↗Related Errors
Provider Information
This error code is specific to AWS services. For more information, refer to the official AWS documentation.