It's a bug that will be fixed in a few days.
TurboTax has released a FAQ on this issue - scheduled for 4/5/2019
Excess 401(k) Contribution Preventing e-File
https://ttlc.intuit.com/replies/7327357
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**