Hi,

Please make sure you're using latest version of Soledad - version 7.4.0

If not, Please remove the code at the end of functions.php file like on this image: http://prntscr.com/uon4qx ( if you don't see it, you can ignore this step )
After that, do following this guide to get auto-updates for the theme: https://pencidesign.ticksy.com/article/15633/

When you done, go to Appearance > Widgets > drag & drop widget "Soledad Instagram Feed" to "Main Sidebar" ( replace with your old Instagram widget ) > click on URL to get Instagram Token & ID and fill it to the fields & do other configs > save and check it again.

Best Regards,

PenciDesign