Error: Error ValidationException: One or more parameter values were invalid: Type mismatch for key X expected: S actual: M
Answered by Rafal Wilinski
Solution
When trying to put or update an item to DynamoDB, you might have tried to write it with incorrect attribute type for example number instead of string or the other way around.
Even though DynamoDB is schemaless, at the table creation you had an ability to specify some AttributeDefinitions. They need to be preserved for all the items in the table.
Other Common DynamoDB Errors (with Solutions)
- dynamodb does not accept empty set
- dynamodb query is null
- dynamodb system errors metric
- dynamodb index does not exist
- moto dynamodb not working
- dynamodb localhost not working
- dynamodb the parameter cannot be converted to a numeric value
- dynamodb scan missing values
- dynamodb table did not stabilize
- ImportError: No module named boto3 (DynamoDB)
- is not authorized to perform dynamodb:* on resource
- an expression attribute name used in the document path is not defined
- dynamodb problem function call failed
- why is the GSI dynamodb not showing item count
- Float types are not supported. Use decimal types instead.
Dynobase is a Professional GUI Client for DynamoDB
Start your 7-day free trial today
Product Features
DynamoDB Tools
DynamoDB Info
© 2026 Dynobase