Error: DynamoDB ConditionalCheckFailedException

Answered by Rafal Wilinski
Solution
In DynamoDB, when writing operations, Condition Expressions can be specified to determine whether operation should be actually performed.
ConditionalCheckFailedException is an error thrown by AWS SDK or CLI when the ConditionExpression evaluates to false. This is especially useful if you want to atomically check data without fetching and then writing. Examples include:
- Create an item if such doesn't exist yet
- Delete an item only if some attribute is defined
- Update user attribute only if user is active
Either remove ConditionExpression from your DynamoDB code or change parameters and data so the condition can be satisfied.
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