When migrating EPM 20010 to EPM 2013, after migration many project in project centre are not able to update by project manager, below error message shows to user.

"an error has occurred when saving your project to the server,.."

Below the packages including SharePoint Server 2013 SP1 and Project Server 2013 SP1 after that  bug has been fixed

https://support.microsoft.com/en-us/kb/2880556

List of all Service Pack 1 (SP1) updates for Microsoft SharePoint Server 2013 and related server products

 

Microsoft SharePoint Server 2013 Service Pack 1

DownloadDownload the 64-bit update now.

2880552 Description of Microsoft SharePoint Server 2013 Service Pack 1 (SP1)

Microsoft Project Server 2013 Service Pack 1

DownloadDownload the 64-bit update now.

2880553 Description of Microsoft Project Server 2013 Service Pack 1 (SP1)

 

https://support.microsoft.com/en-us/kb/3114345

December 8, 2015, cumulative update for SharePoint Server 2013 (KB3114345)

 

https://support.microsoft.com/en-us/kb/3114341

December 8, 2015, cumulative update for Project Server 2013 (KB3114341)

 

After installing all these patches please run the SharePoint Products Configuration Wizard to complete the installation as described in https://technet.microsoft.com/en-us/library/dd239177(v=office.14).aspx