Dear community, I have already tried to use to search function, but it did not helped me out. It also seems that there are multiple ways of fixing this problem. Situation: I have a Windows 7 workstation with Microsoft Outlook 2010 When I start outlook 2010 with an existing ( just created ) mailbox, it returns with an error: Cannot start Microsoft Outlook. You must connect to Microsoft Exchange with the current profile before you can synchronize your folders with your outlook data file (.ost). I am getting pretty frustrated since I never get problems with exchange and now this all sudden happens. I have tried many things, I searched this whole forum database for solutions but really all "answers" did not help. My setup: Windows 7 workstation ( Outlook 2010, registered on domain ) Windows Server 2008 R2 64 ( Exchange Server 2010, PDC ) What do I need to do in order to get rid of this error message. Thank you

Hi, It sounds like there is already a profile created in Outlook - with an existing ost file. If you don't need the data in that file you could try to delete the Outlook profile and then start over creating a new profile. Leif

Thank you for your reply, But unfortunately this did not solve my problem.

Hi Rootrunner, Just provide two solutions for your reference: 1 In short, you need to tell the MAPI profile to prompt for your credentials, so that you get authorized by the Exchange Server properly. Go to Control Panel -> (View 32-bit Control Panel items, if you are on 64bit) -> Mail Got to your profile that is suppose to connect to this customers Exchange Server and select “Always prompt for logon credentials”. Now, when you start Outlook you will have to enter your domain\Username credentials and password. 2 Click Start, click Run, type regedit in the Open box, and then click OK. Locate and then click the following subkey: HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\RPC On the Edit menu, point to New, and then click DWORD Value. Type DefConnectOpts, and then press ENTER. Right-click DefConnectOpts, and then click Modify. In the Value data box, type 0, and then click OK. Exit Registry Editor. Hope they help. Best Regards!Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

This registration value does exist HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\ but the RPC never existed before and isnt there atm. I created a new key named RPC with a new DWORD "DefConnectOpts" with an value of 0. Restarted the system, still no effect.

Dear community, The problem still persists, I have litterally tried every single solution to fix this. Renaming .OST to ost.old = doesnt work Outlook does not create any PST files = no idea why it doesnt removing profile and then adding a new one = doesnt work adding registry keys for RPC = RPC never existed and they dont after exchange/office 2010 installation, so I dont know why people are referring to RPC subkey. Creating new mailbox in exchange = doesnt work restarting exchange = doesnt work restarting outlook = doesnt work Clearing all configuration data and reconfigure the client/server connection = doesnt work removing all local outlook files and make a complete clean office 2010 installation = doesnt work removing exchange server 2010 from the 2008 R2 server and then install a clean copy = doesnt work There has to be a solution, please.

1. Is this for all users or some? 2. Is this on the same PC or different PC with the same user or a different user?Sukh

I have made 1 user which is Me. not the administrator. There is only 1 user, I wont make more until this ones fixed. The user logs from a laptop onto the domain. His profile settings are going good and are located on the server. But when I start outlook just, default settings and it isnt working.

1. testing with one use isnt enough, what if you create a new users and test, or a few test accounts and test. 2. Also what about my point to above, test that, or use another laptop and test that tooSukh

I have made 5 new users and tried to let them log onto the domain. That went succesfully but when they open their outlook. The same message pops up. I made a clean server 2008 R2 install, a clean ( from microsoft ) Exchange 2010 server install. Besides that I have made a clean Windows 7 install with a clean trial version of Outlook 2010. Still the same error, I can not believe this.

All the above attempts failed to fix my problems... Situation + fix as follows: ( It did fix for me ) You have a Server 2008 R2 server with Exchange Server 2010. You have Windows 7 and Outlook 2010. You get multiple errors regarding OST / PST files or Sync errors towards your exchange server. Fix: Clean install of your Server 2008 R2 and Exchange 2010 ( DO NOT EVER INTERUPT YOUR INSTALLATION ) because I did and Exchange said after the installation that everything went ok, but it definitly did not went ok. Leave all settings default after clean install Your first priority is to create local/roaming files for your users, so let them log onto the domain and start outlook. Outlook asks for some credentials. Now send couple of mails for test. Configure your mailclient to your likings. Now you can start creating relay's in ur xchange if u want.