Issue:
The following error message is seen while launching Web TimeSheet integration Manager for MS Project server.

Unable to connect to MS Project Server. Invalid Account

This error shows up despite the user entering the correct credentials.

Cause:
When you launch Web TimeSheet integration Manager for MS Project Server, under Project server account option you are expected to select either Use Windows user account or Use a Project Server account.

When you have Windows user account option selected on MSPI (Microsoft Project Integration Manager), then the domain account used to access MS Project server and Windows domain credentials used to log onto the computer, should be the same. The error message usually pops up if there is a mismatch.

Solution:
Either you have to create a new windows account which matches the MS Project server domain account.

Or

Create a new domain account on MS Project Server which matches your windows login credentials.