Project Server 2010: Don’t Trash the Cache!

I was going to use the title asking ‘why are people still deleting the cache?’ until my colleague Corrie came up with this much better one!  Rather than asking why you are still doing it – I am telling you not to!

I know there is a lot of history behind this one, and for those of you that used Project Server 2007 in its early days there were some challenges such as the ‘check-in pending’ saga that got people in to the habit of deleting the project cache.  We fixed the problem, then we fixed it again (and again) and you should not generally be seeing any issues with leaving your cache alone to do its job.  However, many customers I talk to are routinely deleting the project from the local cache before they open it and then again after they close it! Why!?!  Its job is an important one – it saves you having to pull that data from the server again – which will reduce network traffic, the hit on both the web services and the database, which means they can be getting on and doing useful stuff.

I’ll also address a miss-conception misconception (thank you Trevor – not addressing the misconception that I can spell…) here that I have heard from a number of customers – the choice of where to load the project from – cache or server?  You don’t have a choice – Project will load it from the cache if it is there, and then load any incremental pieces it needs from the server, to get you the current version of that plan.  In the screen shot below:


the line actually reads ‘Retrieve the list of all projects from Project Server’.  It does not also read – ‘…and open any I might choose after clicking this link from the server and ignore the local cache’.  You don’t get the choice and you don’t need to choose.

I’m sure many of you will not have read this far before clicking the comments option to tell me of all the problems you are having.(and I’m sure some of you are still having problems).  First check that you have the latest cumulative updates and service packs.  If you are still really having issues unless you delete the local cached copy then we certainly need to hear about it so we can fix the problem rather than have you waste your time and system resources doing things that you should not need to do.

I will admit that there can be times when as support engineers we will ask you to remove your local cache to troubleshoot specific scenarios.  The cache itself also has intelligence that allows it to decide that it may have some bad stuff – and it will get a new clean copy of data from the server (symptom of this will be several files in the cache directory with 1,2,3 etc. at the end).  There have also been a few bugs we have worked on recently which ONLY surface when the user has cleared their cache!

So please, if you have been deleting your cache as a matter of routine, then either stop – or speak to your PMO or IT people and ask why they have you do this – and if we need to fix something else then we can take a look.

Comments (51)

  1. Shane O'Hanlon says:

    Great post Brian. Very topical

  2. Paul Mather says:

    Great post Brian, will be useful to send to clients when advising them not to delete the cache! One quick question though, how do you force / synchronise a job in the Project Professional Active Cache that is Ready for Processing? Post here:…/1831b230-3e69-46b5-8c6b-211fa391ee5f

    Any ideas?

    Many thanks


  3. Sylvain Jacquet says:

    Thanks for your post Brain. Indeed, cache management in Project Server (2007) has improved dramatically since RTM with the different patches. However, even in PS2010, we still run from time to time into yet the same issue where the cache says the project is checked out while it's not.

    In your experience, what are the root causes of this particular issue? Users closing the Project Professional application too fast? Any other reason or good practices that would prevent that from happening?

  4. Thanks Shane, Sylvain and Paul for the feedback.  Generally the issue is the message from the server to confirm the check-in never gets back to the client.  Leaving Pro open to confirm the check-in would certainly do no harm – but we have already changed some code that should keep the channels open to complete the process.  Part of the reason for this posting was that we do hear anecdotal stories that it is still a problem – but I'm guessing most people have just stopped telling us as the cache delete is such a well known workaround.  I'm making enquiries internally on any 'lighter touch' alternatives we can offer.

  5. Jean says:

    There are still occasional problems with the cache, for sure … Delete can still solve many problems, especially with PS 2007.

    During 2 years, removing the cache was the only way to try to run the tool … and despite the many patches announced (from CU in CU), not the problems have disappeared completely … You have to understand clients: Microsoft lost the battle of trust. I think we should still be wary of a too angelic speech …

  6. I fully agree Jean – by not addressing the initial problem we (Microsoft) lost trust in the cache (to the degree we often get support calls asking how to turn it off! – and no, you can't turn it off).  My posting was deliberately provocative to get feedback on where we stand now, and hopefully to get most of the Project users to give the cache a chance – and the remainder to tell us what is still broken.

    Best regards,


  7. Probably should have worded that differently – Microsoft lost the user's trust in the cache.  Reading it back I see that my original words could be misinterpreted.  I never lost trust (but I did once in a while need to delete it…)

  8. Adrian says:

    Brian, do you deem it save to delete the cache by deleting the cache directory? I.e. not just delete single projects from the cache via File/Options/Save/Cache/Clean up Cache, but delete the whole ..MS Project14Cache{long_GUID_here} folder?

    If that is deemed unsafe, then the immediate conclusion would be that any new MS Project client user in your environment would be a hazard as well, since those users seem to be in exactly the same situation as a user who has just deleted their cache folder completely.

    Are there any observations regarding this scenario, or am I just missing something and drew an invalid solution?

    Thanks for your effort and kind regards,


  9. Great question Adrian, and the same also applies to any project you open that isn't already in the cache.  Apart from the obvious data loss potential if there are projects checked out to you that only exist in your cache, there is nothing iherently unsafe about clearing the cache, or even deleting the folder, or just creating a new profile (which will give you a new cache directory).  The point I was trying to make was that it is not something you should need to do, and it has some performance consequences when you do it – it makes the server, client and network work harder.  I mention some bugs that appear to surface only when customers clear their cache – and yes, these same things could happen if you have no cache copy of the plan you are opening. No more to share currently on these bugs apart from the fact that you are less likely to hit them if you don't clear your cache – and we are working hard to fix them.

    Best regards,


  10. Hi Brian, what would you recommend for a citrix / Terminal server environment with roaming profiles? If a user is using the defualt cache size of 1,276 MB this will severely increase the logon time for the session. What would be the recommendation in this scenario?

    Thank you in advance


  11. Hi Lee,

    It is a while since I've done much with Citrix, but I'm assuming from the wording of your questions that the cache would need creating each time a user logged on and would not be available across sessions?  Actually creating a cache is the easy part – and regardless of the size if will take a very short time (the default size is related to total disk space rather than constant – but is a limit rather than the size of anything that gets created at log in.  The bad part is that every time the user logs on then the Enterprise Global Template would need downloading, and of course every plan they loaded would need to be pulled from the server too – so no benefit would be gained from the cache.  If it is possible to configure with a cache that will still exist next time the user logs on then that is preferable – but in a Citrix farm environment this could either end up with multiple cache files (which isn;t a problem – Project can hanle this) or cache files on a central network location – which again will not get best use of the 'local' cache.  Hopefully this gives you an idea of what can be slow in this environment. One other consideration is that when saving and closing the local cache will communicate with the server – not sure if there are some bad practices around on closing Citrix sessions without closing and exiting correctly – but certainly seen some save and check in issues in Citrix environments.

    Best regards,


  12. Hi Brian,

    Thank you for the quick response. The client would like to not have the Project Pro cache stored within the users roaming profile due to the increased logon time. What would your thoughts be on having a local cache per Citrix server, for example: if the client had 6 Citrix servers in a load balanced farm a user could have 6 different cache files (1 on each Citrix server). What would you recommend as the minimum cache size for Project Pro 2010? We have seen an article from Christophe for Project Pro 2007 stating 200 MB is the minimum recommended.…/managing-project-professional-s-active-cache-size-and-location.aspx  

    Thank you


  13. Hi Lee,

    That sounds like a good solution.  They still would not always be guaranteed the latest version of plans in their cache – but the server would just know what they needed.  Assuming the Enterprise Global was not changed that often this solution should mean they would not be having to download each time.  200MB should be fine – and you could always monitor actual usage to see if a different size was needed.

    Best regards,


  14. Hi Brian,

    Many thanks for your help with this issue.


  15. Johan van Wyk says:


    We routinely see that files need to forced checked-in due to the cache becoming out of synch. I typically always retrieve the newest list from PS and then open the files. We are experiencing a fair amount of synch issues. So I do not think your implementation of the cache was a huge success.

  16. Thanks for the feedback Johan – and I'll accept the criticism, but also tell you that you are always using the cache – even when you select from the list of projects you have pulled from the server.  Nowhere do we say 'open' from server – and you have no option (assuming that the project exists in the cache).  So perhaps the cache isn't as bad as you suspect ;).

    Best regards,


  17. Paul MC2 says:

    There is a resource problem if you do not delete the cache in project server 2010. It needs to be deleted in order for updated resource information to be displayed in project client.

  18. Paul, can you be a bit more specific?  There is certainly a problem if you need to delete the cache – you should never need to delete the cache in normal operation – and if you do then we need to fix the real issue, not cover it up with dangerous processes that can really lose data.



  19. Hessel says:

    Is deleting the cache the same as using the "clean up cache" in  Professional?

  20. Yes, Hessel, same thing, although often customers will delete the whole cache via the OS by deleting the directory, or individual plans via the files in the cache, rather than using the UI.  Deleting the Project Server profile and re-creating would also have the same effect.

    Best regards,


  21. Ryan Darby says:

    The difference between deleting the cache in MS Project, and deleting the folder itself, is that there seems to be more stored in the cache than just the projects. If the network drops, sometimes it won't go back online until the cache is cleared. It seems that connection information is stored in there too.

    There may not be a reason to clear the cache normally, but when you have connectivity problems you do need to do it.

  22. phu ha says:

    Good evening Brian, I would like to ask you one question about my project system.

    I have multiple projects under one PWA, these are the projects that my student create by using the template that I created for them. So each team will have their own project and can only view their project only when they login to PWA ( I did it by using the security templates that I modified a little bit). But the problem appeared today, that one of my student discovered that they can view all other groups project just by using Project professional and open from Enterprise project with this "Retrieve the list of all projects from Project Server".

    how can I stop it? so the student cannot access projects by using this functions anymore. I tried to look around, read some chapters but no use.

    Thanks you so much and have a happy thanksgiving.

  23. Peter says:

    I have multiple projects, and I want the project’s PM can only see their project only, not other group project. I can do it in Project web access, but if the PM using this function

    “Retrieve the list of all projects from Project Server”, they can access other groups project. How can I prohibit, restrict this function?

    thanks you so much and have a blessed holiday.

  24. peter says:

    I tried to post several times but failed.

  25. Hi Peter, Phu Ha, if categories and permissions are set correctly then it should be possible to restrict the projects listed from the server. Review the article at…/cc197354(v=office.14).aspx – that explains the various options.

    Sorry for the delayed response – away for the long Thanksgiving weekend – and postings recent comments hadn't been published.

    Best regards,


  26. Jef Guertin says:

    Hi Brian,

    I can still see this behavior where the cached version of the project still shows "Check-in pending" with multiple different users. Most of the users experiencing this problem are newbies. After discussing with them, it would seem as if they were "exiting" MS Project Pro instead of "closing" each project individually and then exiting MS Project Pro.

    We are currently using:

    -Project Server 2010 SP1 with August 2012 CU

    -Project Pro 2010 SP1 with August 2012 CU

    Is this fix in another CU? Or is the only "fix" a matter a reinforcing the behavior of closing each projects before exiting Project Pro?



  27. Hi J-F,

    There aren't any other fixes for this – but I agree there still appears to be a bug that gets exposed when working the way your users are.  The quickest solution would be to not do it – but if any Premier customers are getting frustrated by this behavior and have a consistent repro I'd be happy to push for another fix.

    Best regards,


  28. Jef Guertin says:

    Do you still see this behavior in Project 2013?  If yes, I would push for a fix that would resolve both versions.  If not, then I will ask my client (750 PWA users, 40-50 Project Pro users) if he does not mind waiting for the Project 2013 version.

  29. Jef Guertin says:

    … oh and almost forgot, I think you are doing a great job on these forums and helping out where you can. I don't know how you do it but you always seem to be right there, ready to answer.  Thanks for your help Brian!

  30. Mark Middleton says:

    We have had several clear examples where we had a problem that was solved by deleting the cache in Project Pro. In one case (found by several people, w/several Project files and several PCs), trying to use the filter failed, as soon as the cache was cleared that problem went away.

  31. Hi Mark, yes unfortunately there can be some valid reasons why you will need to delete he cache – not familiar with the filter issue – perhaps there is another way to resolve it – just saying if you do need to delete the cache then take care – it could be the only place certain changes to a file exist if they have not been saved.

    Best regards,


  32. Jeff says:

    When projects are deleted from the server they remain in the cache. Over time, the cache is filled with outdated information. Why wouldn't you delete it?????

  33. Good point Jeff, my article was more about using deletion as a means to overcome some issue with the plan rather than just housekeeping.  By all means remove data for projects that no longer exist on the server – but just take care.


  34. Hi Brian,

    Is this still an active thread?  We routinely advise our PM community to perform a File > Close of their project(s) before then closing the application, however we are still getting several reports of the Project already being checked out when the user attempts to open it the next time.  As a result we have to advise removing the project from the Cache before they can edit it again.  

    I have also experienced this first hand by closing and saving a project, leaving Pro open, then checking the status of the Cache which shows the project is still checked out.

    We are on the June 2012 CU for Project Server and Project Professional (14.0.6123.5000).



  35. TB says:

    Brian, the only situation that I have seen that cleaning cache helps is when you add new values to enterprise custom field lookup tables and users cannot see those new values when they open projects.  Once they clean their cache, not via the options tab, but by navigating to their cache folders and deleting the remnants there…then the user restarts Projec Pro and they get a new enterprise global with the new lookup table values.  It's the only way some users can get a fresh copy of the global.  If you have another solution, I would love to hear about it.  This seems to be an unpredictable problem and happens to some users but not all.  All updates and hot fixes are current and the problem still manifests itself with some users.  There seems to be no other way to fix the issue.  Using the 'clear cache' buttons under options is not a solution.

    Thoughts?  Tom

  36. ReneJ says:

    Thank you for confirming some technical myths!

  37. Peter says:

    It would seem that this post is no longer being monitored but thought I'd still post in case someone was listening 🙂

    In my organisation, we are using Project Server 2010 and we regularly still have users experience to situation wher they close and check in their schedules but the cache still thinks the project is checcked out.  The projects are not checked out and connot be force-cheked in.  The only way to resolve the issue and allow the Project Manager to open the schedule in read/write mode is to clear their cache.

    We also find that simply removing individual projects from the cahce doesn't always resolve the issue and I always advise the user to remove the entire cache folder. This always fixes the issue.

    Note: we instruct our PMs to always close the schedule using File > Close and NOT the white-on-red cross at the top right.

    This is an extremely frustrating issue and occurs frequently.  It is not an isolated matter.  I assume that given Project Server 2013 is here, that further fixes to PS2010 are unlikely.  Is that correct?



  38. HI Dave, Tom and Peter, sorry in being remiss in keeping up on this thread.  Nothing new to report – if someone comes up with a detailed repeatable repro of this issue I would love to push this for a fix.  So far I haven't seen this.  Peter – we will still be taking fixes on 2010, our priority on fixes are those requested by customers having a premier support contract – if your company has one and you have a solid repro then get your TAM to help you request a fix.  Please, please don't just remove the whole cache directory.  If your users happen to have any of their plans actually checked out and have worked on them then you will be losing their work!

    I have heard that having both client and server patched to the exact same level has helped some customers avoid this issue – and though I can see no reason why this should help – I don't discount something that appears to work.  Interested to hear if this is something that might work for you.

    Best regards,


  39. stevecraig55 says:

    Does anyone have a suggestion of how to retreive missing MS project 2010 files from the cache?  I have a copy of all the .mpc files, which are not visible on the Server, so I want to convert these to .mpp files and re-load them to the server…

  40. Hi SteveCraig55 – this should work.  Open Project Professional and connect to your server.  Go to File, Info, click the drop down on the Manage Accounts button and select Work Offline.  If you now click File, Open you should see you files listed that are still in your local cache even though they are not on the server.  You can then select File, Info Connect to Server – then you can use Save-as to save back to the server.

    Hope this helps,


  41. stevecraig55 says:

    Many thanks Brian – that worked perfectly. got the file recovered.

  42. Barb says:

    We recently created an add-on to our PS Project Pro (2013) install package to remind users to save, publish and check-in.  The hope was to improve the adoption of our 'best practices' – to save, publish and close each time you are finished editing — AND also hope to reduce the 'check-in pending' issues we are still seeing.  I would like to see Microsoft add this functionality into the product.

  43. Fredo Maximo says:

    If you fixed it the problem again and again, then something's still broken.  I'm running Project 2013, and I get the check-in errors repeatedly.  The only thing that clears it up is a cache deletion.

  44. Couldn't agree more Fredo.  Tells us exactly how you can make the error appear on demand and we can see if we can fix it properly!

    Best regards,


  45. Chris says:

    Hi, We have an issue in our VDI environment where the cache is on a shared network drive, but the network isn't necessarily reliable. Users open projects, work for a while, but then they try to save and they no longer have an active cache, because the network dropped and then came back on. What are the requirements for Active Cache connection, and can the connect be reinitialize without users loosing their work?

  46. Plan A says:

    Hi Brian

    I’m having an issue in project server which is threatening a very important plan! I have a plan in server which I am using to give a high level summary of several smaller projects also on the server. The external dependencies were working well all though time consuming to build and all was well until the check in for one if the sub projects would not happen after project crashed during a save.

    I was advised to clear my cache to enable me to force check in and I have and it’s worked.

    Great. Except that now external links to some plans work and update my schedule automatically but others don’t. The successors are still there and are referencing the right task with a grey ghost task showing but the dependencies just don’t seem to be driving my schedule.

    Sorry for the long winded question, I am new to project server but not to project,

    Any help would be appreciated! Thanks!

    1. Hi, I’d suggest recovering the plan from a saved copy in the archive if the good data is likely to be there. As this document mentions – if a save hasn’t worked then clearing the cache is never a good idea – and that will have lost data. If the good data isn’t in the archive (or your administrator doesn’t have archives running) then the only thing would be to re-make the broken links.
      Best regards,

      1. Plan A says:

        Hi Brian huge thanks for replying! The sub projects which aren’t feeding are also alerting me to a circular reference since the crash. Could this be part of the problem?

        Thanks again

        1. The circular references certainly point to a problem, as mentioned – best to get back to a clean copy as you may find other issues with this plan later if you try and repair and move forward with it.
          Best regards,

  47. Peter Brundish says:

    I have a number of PMs who have the error message in Project Pro 2013 that a check-in has not completed; this only prevents them from opening the project in MSP, several have edited in Project server after the last time of editing in project. Clearing the cache removes the obstacle to opening the schedule from the enterprise

  48. Dave says:

    Hi Brian – occasionally we have situations where the status bar text in Pro disappears (e.g. “Save job 64% complete”) part-way through the Publish process and it seems the only way to check if the project has published is to click on File > Info and seeing the last published timestamp. Do you know why the status text would be disappearing randomly?