Can't enter my 1099 into system, it says something went wrong and returns to previous page

Sounds like a web browser issue.  Clear cache and cookies on your web browser and then try to enter the form again.

See this TurboTax support FAQ for clearing cache - https://ttlc.intuit.com/turbotax-support/en-us/help-article/product-system-requirements/clear-cache/L8EEqjh3R_US_en_US?uid=lu2uwzcf

See this TurboTax support FAQ for cleating cookies - https://ttlc.intuit.com/turbotax-support/en-us/help-article/data-systems/delete-cookies/L009gaGqG_US_en_US?uid=lu2uy2af

If this does not correct the problem then change your web browser to one of these you are not currently using - Google Chrome, Mozilla Firefox, Microsoft Edge

Did you try to import it or type it in manually?  

Try clearing your cache and cookies in your browser.

Your browser stores recently visited webpages as temporary files in a cache, which enables the pages to load more quickly when revisited.

However, a full or corrupted cache can cause problems in TurboTax, so sometimes you need to clear your cache (that is, remove these temporary files).

Here are the official instructions for the most popular browsers:

• Google Chrome
• Mozilla Firefox
• Microsoft Edge

Apple's official support site doesn't appear to contain instructions for clearing the cache in Safari. Your best bet is to search the Internet for clear Safari cache or similar search terms.

Cookies are small files that temporarily store data on your computer. We use them to personalize your experience so you see information you already entered and not items that are irrelevant or repetitive.

On rare occasions, they may make your browser think you already did something that you still need to do. To fix that, you'll need to delete (clear) the cookies from your browser.

Each browser has a slightly different method for deleting cookies. Choose the browser you're using:

• Internet Explorer
• Mozilla Firefox
• Google Chrome
• Safari
• Safari for iOS (mobile devices)

TurboTax FAQ: How to clear your cache

TurboTax FAQ: How do I delete cookies?