A
AdyenAdyen 21
Not Submitted
Technical
System or connectivity issues
Retryable
This decline may succeed on retry
Description
The transaction was not submitted correctly for processing.
Recommended Action
Resubmit the transaction.
Common Causes
- Incomplete or malformed transaction data
- Integration issue
Recovery Tips
- Check the API request for missing or invalid fields
- Resubmit with corrected data
Quick Reference
Code
21
Category
Technical
Retryable
Yes
Source
Adyen
Recoverability verdict
21 is often recoverable
Payments failing with code 21 are often recoverable with the right retry timing and routing. Slicker recovers up to 70% of soft declines with smart retries.
Related Decline Codes
2Retryable
Refused
The transaction was refused by the issuer without additional information.
3Retryable
Referral
The issuer requires a referral — typically a voice authorisation or manual review.
4Retryable
Acquirer Error
The transaction did not go through due to an error on the acquirer's end.
7Retryable
Invalid Amount
An amount mismatch occurred during the transaction process.