I am trying to find a way how to update a SharePoint solution programmatically with C#. (I already know how to do this with the powershell command Update-SPSolution).
I have tried using this code but it doesn't work:
SPSolution sol = SPFarm.Local.Solutions[name]; //name = mytest.wsp
sol.Upgrade(filePath); //C:\mytest.wsp
Can anyone provide some guidance?
You are using the correct code (see http://msdn.microsoft.com/en-us/library/office/ms455619.aspx). When I do this, I usually specify DateTime.Now for the second parameter. This code schedules a deployment job the same way the Update-SPSolution Cmdlet does.
What I would suggest is to run this code and then immediately refresh the Farm Solutions page to see if there is a change in status. Additionally you could use this PowerShell to see if a deployment job exists:
Get-SPTimerJob | Where-Object { $_.Name -Match "solution-deploy" }
Additionally you can check the solution itself for an existing job:
(Get-SPSolution solution.wsp).JobExists
