Clear cache and cookies on your web browser.  Close the browser.  Relaunch the browser.  Access the TurboTax online website again - https://turbotax.intuit.com/personal-taxes/online/

If the problem persists then change your web browser.

Sign off of TurboTax.  Clear cache and cookies on your web browser.  Close the browser.  Relaunch the browser.  Sign back onto your TurboTax account and go to the File section for Step 1 and click on Revisit.  Go through all 3 Steps and e-file the tax return by clicking on the large Orange button labeled "Transmit my returns now" - https://myturbotax.intuit.com/

If you get the same problem, then change your web browser.