OST file has wrong association

Question

_{Wednesday, August 16, 2017 3:58 PM}

I had someone help me with my outlook and (I don't know how) but now my OST files show they are Adobe Documents. Outlook still uses them but they show the Adobe icon and in properties they say Type of File: Adobe Acrobat Document. I've went into Systems, File Association - and looked up OST extension. When I click on the Adobe Icon to change it to Outlook it  only allows me to search in the store for file type. Any help is appreciated.

All replies (7)

_{Friday, August 18, 2017 2:44 AM ✅Answered | 1 vote}

Hi Axsom,

I found I have the same issue with you.

When I check my .ost file, they appeared as Adobe Reader icon. Change associate type will bring error which is same with you. But, after I uninstalled Adobe Reader, .ost file changed as Outlook icon now. Yeah, it is associate with Outlook now.

I suspect you might open this type file with adobe reader careless before or adobe reader tampered default file association after you download it.

However I have not install Adobe Reader again, you could try to reinstall on your side and share the result with us.

Bests,  

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_{Wednesday, August 16, 2017 4:56 PM}

Try right click on the file and then click on Propertise and then click on change Default program.

_{Thursday, August 17, 2017 9:14 PM}

I wanted to use a SS to show you what I get but I'm still not verified yet. I did request to expedite it

I'm pointing it to OULOOK.EXE and it till says the "The program you have selected cannot be associated with this file type. Please choose another program."

_{Friday, August 18, 2017 1:50 PM}

Doing the uninstall of Adobe did re-associate my files back to outlook. Thank you. Before I mark this as solved, I'm going to reinstall Adobe and report what happens. It will be several hours before I can do this as I have to get to work...

_{Friday, November 17, 2017 4:34 PM}

Uninstalling Adobe does restore the .ost files to Outlook. However, after reinstalling Adobe the .ost files revert to Adobe Reader Document type. I presume that the association is still in the system, but where? Is there any answer to this?

_{Friday, November 17, 2017 4:43 PM | 1 vote}

Have found a solution that seems to work for me. Reset the defaults to the Microsoft recommended ones.

In Windows 10 - Settings > Apps > Features > Reset to Microsoft Defaults. Then for Mail set Outlook as the default again.

Regards

_{Thursday, April 4, 2019 6:16 AM}

This worked great. Easy to do as per your direction and no downside or bad side affects.

Thanks very much!