In SharePoint 2010 environments that have Power Pivot for SharePoint, this error will occur if the application-level solution for Power Pivot did not deploy correctly.
|Applies to||Power Pivot for SharePoint|
|Product Version||SQL Server 2008 R2, SQL Server 2012, SQL Server 2014|
|Cause||Powerpivotwebapp solution is not deployed or did not deploy correctly.|
|Message Text||Could not load file or assembly 'Microsoft.AnalysisServices.SharePoint.Integration'|
Power Pivot for SharePoint uses solution packages to deploy its features on a SharePoint server. One of the solutions is not deployed correctly. As a result, this error appears whenever you try to open Power Pivot Gallery or other Power Pivot application pages on a SharePoint site.
Deploy the solution package.
In Central Administration, in System Settings, click Manage farm solutions.
Click Deploy Solution.
Choose the web application for which this error is occurring. If there is more than one web application, redeploy the solution for all of hem.