I encounter the same error in March 2026 to file my 2025 tax. After google search but not finding a good resolution I ask ChatGPT and the answer is. pretty good also much easier to follow:
How to fix it
✅ Option 1 (Best): Enter summary totals instead of individual trades
- Go to your 1099-B section in TurboTax
- Delete the detailed transaction import
- Re-enter using:
- “Enter a summary for each category”
- Use totals from your 1099-B:
- Short-term covered
- Short-term noncovered
- Long-term covered
- Long-term noncovered
👉 Then:
- Attach the full 1099-B PDF (TurboTax will prompt you), OR
- Mail it with Form 8949 if required
