Unable to open a project schedule from MS Project 2010 in Project Server environment – Schedule opening issue!

Environment: Project Professional 2010 SP1/ Project Server 2010
Issue:

One of my lead scheduler brought up an issue in accessing her schedule using MS Project Professional in Project server environment. When she tries to open a specific schedule on server, she gets the following error

She confirmed me that all other schedules have no issue at all but this one. She was not able to close this window as it freezes the MS Project Pro application. She first tried to kill MS Project application in Windows Task Manager but could not do that and eventually she killed Project (Winproj.exe) from process tab.

When I tried to see the exact error, it showed me the following error that does not help much.

Solution:
The first thing I checked if I am able to see project schedule in PWA (web client). I had no issue in opening that schedule in PWA. 

Initially I tried to restore the last saved specific project schedule from server. I was able to restore with 100% without any issue. I tried again to open the schedule from MS Project client; I got the same error mentioned above so this trick did not help much. Scheduler confirmed that she had no issue when she opened this schedule 2 days ago.

After doing a few tricks, I found the following steps worked for me and my scheduler was able to open the schedule this time without any issue.

Steps:

1-      Login to PWA

2-      Go to Project Center and click the affected schedule link

3-      Click ‘Project Details” PDP link and click ‘Edit’ button from Ribbon to edit project level custom fields.

4-      Click ‘Save’ button to save the project’s custom project fields.

5-      Close and check in the project schedule.

And bingo, scheduler was able to open her schedule without any issue. It looks like something happened during the last saving or publishing process that blocked communication between client and server and caused that issue. After saving the schedule from PWA, it removed all the blocks in the communication with server.