The TurboTax online editions are Only for filing a 2019 tax return.

Did you enter 2018 tax data on the 2019 tax return and e-file the tax return?  If so, another 2019 tax return cannot be e-filed.

You have to wait for the IRS to either reject the return or send you a letter in the mail questioning the tax data entered on the 2019 tax return.

If the tax return is rejected then you can delete the 2018 tax data and enter the 2019 tax date, then e-file the 2019 tax return again.

If the tax return is accepted by the IRS, then wait for the IRS letter and then you will have to amend the 2019 tax return with the correct 2019 tax data.

See this TurvrboTax support FAQ for amending a 2019 tax return - https://ttlc.intuit.com/community/tax-topics/help/how-do-i-amend-a-2019-return-in-turbotax/01/123845...

"after filing for 2018"     Uh oh--I have a bad feeling that you just used the the online software to prepare and e-file a 2018 return----did you do that?  If so--you made a big mistake.  The online software is ONLY for 2019.  If you used it and e-filed, the system is treating it as if you filed a 2019 return and you will not be able to e-file another 2019 return.

If the IRS somehow accepts the return, you will have a mess to sort out.  If the IRS processes your 2018 return which you filed as a 2019 return--you will have to wait for it to be fully processed and then amend it to remove the 2018 income and replace it with 2019 income.

If it gets rejected--which is what you should hope for -- you will be able to clear out the 2018 income and re-do it using your 2019 income and try to re-file it.  You will not have a 2018 AGI to use, so you will probably still have to print sign and mail it.  (You can try using "zero" as the AGI--but it might not work)

Meanwhile the correct way to prepare and file a 2018 return is to use the desktop software for 2018 and then mail the return:

Online preparation and e-filing for 2018 is permanently closed.

To file a return for a prior tax year

If you need to prepare a return for 2016, 2017, or 2018 you can purchase and download desktop software to do it, then print, sign,  and mail the return(s)

https://turbotax.intuit.com/personal-taxes/past-years-products/

Remember to prepare your state return as well—if you live in a state that has a state income tax.

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

Note:  The desktop software you need to prepare the prior year return must be installed/downloaded to a full PC or Mac.  It cannot be used on a mobile device.

If you are getting a refund, there is not a penalty for filing past the deadline.  If you owe taxes, the interest/penalties will be calculated by the IRS based on how much you owe and when they receive your return and payment. The IRS will bill you for this; it will not be calculated by TurboTax.

https://ttlc.intuit.com/questions/1900990-how-do-i-file-a-prior-year-tax-return