QuickBooks import errors are almost always file-format problems wearing vague error messages. Here are the failures we see most, from most to least common.
"Something's not quite right" on a CSV upload
QuickBooks Online's generic rejection. Usual causes: summary rows above the header, a debit/credit split the mapper can't handle, European date or number formats, or stray currency symbols. Converting the CSV to a QBO file sidesteps the entire mapping step — the format carries its own structure.
Desktop rejects the .QBO file
Web Connect files must be structurally exact: correct headers, a bank identifier tag, and properly escaped text. Files renamed from .csv or .ofx, or hand-edited in a text editor, fail validation. Regenerate the file with a converter rather than patching it by hand.
Import "succeeds" but nothing appears
Check the date range filter on the Bank transactions screen first — imported history often lands outside the default view. In Desktop, imported transactions wait in the Bank Feeds Center until reviewed, not in the register.
Purchases importing as deposits
A sign-convention mismatch — common with Amex and Discover exports where charges are positive. Re-convert with the "Flip signs" option and re-import.
Duplicate transactions
QuickBooks dedupes on each transaction's FITID. Files whose IDs change on every conversion re-import as duplicates; our converter derives stable IDs from the transaction itself, so the same data always carries the same ID. If you've already imported duplicates, exclude them from the review screen rather than deleting register entries.