2.0 to 2.1 Migration Troubleshooting
GetHtmlAttributeForLink() method is not defined
Source File: xxx\Website\Areas\ScoreBootstrapUI\Views\Shared\Content\Buttons\_ImageButton.cshtml Line: 28
Solution
This issue happens if Areas/ScoreBootstrapUI/Views/web.config is not updated. Please check that file in your server. You can see old version of that file with name web.config with new version of file is sitting in the same folder with different name. That is standard Sitecore behavior for *.config files in *.update package. Sitecore expects that Administrator goes into files and "activate" every changed file manually.
Please see http://jockstothecore.com/update-config-love/ article for more details.
Please "activate" web.config file manually to solve the issue.