# Plaid ProcessorTransactionsSyncResponse Data Verification Error: modified returned as null instead of array

## The problem

Calling transactions sync in the Plaid sandbox raised a data verification error on ProcessorTransactionsSyncResponse: the API returned `modified` as `null` where the SDK expected an array. A Plaid maintainer confirmed the API was misbehaving and said the fix would deploy the week of January 6th (delayed slightly past the holidays to notify affected customers). The reporter later found more null fields in the sandbox response (account name/type as None), and the maintainer confirmed the server-side fix had deployed.

## The verified fix

This was a server-side bug in Plaid's sandbox, not your code. Plaid fixed the API so `modified` returns an array again - the fix deployed the week of January 6th (announced in the issue thread by a Plaid maintainer). If you still see nulls for fields like account name or type after that date, report it - the maintainer asked for follow-ups since sandbox fixtures can drift. No client upgrade was needed; the same SDK worked once the API response was corrected. Source: https://github.com/plaid/plaid-python/issues/539