Hi Bipin,
Thanks for contacting Syncfusion Support.
We suspect that you are using VS2017 and the reported issue occurs due to referring Nuget package other than Nuget Feed URL and Syncfusion AspNet.Core Feed URL. So, if you have referred any other feed URL, please remove it and refer the necessary Nuget as mentioned in the below screenshot.
If you have already installed our ASP.NET Core Package in your machine, then refer the Nuget feed URL only in Nuget Package Manger window.
If still you are facing any issue, please share the below details
#1) .csproj file
#2) Output window screenshot to show case complete error details when package get restored.
#3) Screenshot of Nuget Package Manger window to check what are the Nuget Packages referred in the application.
This details will be helpful for us to analyze and provide a solution at the earliest.
Regards,
Francis Paul A.