Failed To Locate Reason Engine, Exiting

If you’re having problems accessing Reason 3.0.5 on an Intel Mac after installation and you’re getting the message “failed to locate reason engine, exiting”, every time you try to launch, the likely reason is that your ReWire folder has been set to read only.

You’ll need to change the permissions on the folder to “Read & Write” in order to launch Reason in ReWire mode.

To do this…

  1. Open a Finder window.
  2. Browse your hard drive, going to Library > Application Support > Propellerhead Software.
  3. Control-Click on the ReWire folder and select “Get Info”.
  4. Scroll to the end of the info window and extend the “Ownership & Permissions” (small triangle to the left).
  5. Change the permissions in “you can” to “Read & Write”.

If you can’t change permissions, or the box is greyed out, you’ll need to change the owner (or I did anyway). The default is set to ‘system’, click the lock beside the Owner dropdown and select your username from the menu. You’ll see the permissions box is no longer greyed out. Click the lock to prevent further changes on ownership and set the permissions to “Read & Write”.

Go back to wherever you dragged your original Reason Adapted 3 folder to (I stuck mine in Applications) and launch Reason, problem free.


  1. Danny March 6, 2008 at 4:17 am

    YESSSS! Thank you! Big help

  2. Ken McGuire March 6, 2008 at 8:45 am

    No worrys Danny, glad to be of help.

  3. Brockbeats April 7, 2008 at 4:30 pm

    Hey Ken I’m having the same problem & I’ve done everything that you posted & I’m STILL getting the “Failed To Locate Reason Engine, Exiting” message. Do you have anymore suggestions?

  4. Ken McGuire April 7, 2008 at 4:38 pm

    @brockbeats Afraid not. The write permissions seemed to do the trick with me and since then I haven’t had any issue at all (or come across someone who had the problem and it wasn’t the write-protect issue!), sorry I can’t be of much else help in this case!

  5. Brockbeats April 7, 2008 at 4:55 pm

    Thanks anyway Ken, I just have one more question. When I followed your instructions & clicked on “Get Info” (even though on my mac it says “More Info”) the Owner & Permissions screen comes up as you said it would. I selected my username & changed the Access to “Read & Write”. However, underneath that (still in the Ownership & Permissions drop down) there’s another selection that says Group that has “wheel” as a default. Under that I see Access that has “read only” as a default. Do you think I need to change any of these settings also?

  6. Ken McGuire April 7, 2008 at 5:10 pm

    @brockbeats If your user is part of a group, change the user permissions just in case – worst thing you can do is try! Can’t say that I noticed group permissions on my own at the time. Looking at it now, the group is greyed out and is the same as the admin name, again with read-write permissions.

    Can’t hurt to try, just in case!

  7. Brockbeats April 7, 2008 at 5:18 pm

    Thanks Ken I’m trying now.

  8. Aaron Kook April 8, 2008 at 1:38 pm

    Worked perfect! Thanks!!!

  9. Brockbeats April 8, 2008 at 3:55 pm

    Thanks again Ken it finally worked. I had to trash the REX & ReWire folders then relaunch Reason.

  10. Tom July 8, 2008 at 1:55 am

    this was pissing me off no end!

    im so glad all the things you guys said helped me. i couldnt find out anywhere how to do it.

    try everything. then brockbeats said he trashed rex and rewire folders and it worked, i tried and now its working fine on my mac book!



  11. halfunction September 25, 2008 at 4:40 am

    Thank you sir! you have cut through the BS and given a clear and concise solution to a problem that has plagued me for days! I have scoured the propellerheads site and I could not find this information anywhere.

    Someone should really tell them about this issue.

    A million thank yous and I hope have a wonderful day!

  12. Ken McGuire September 25, 2008 at 12:42 pm


    You’re most welcome.

  13. Aconite Will October 24, 2008 at 4:08 pm

    dude…. you just saved me from banging my head against the wall for the 100th time.

    so quick. so easy…..

  14. Ken McGuire October 30, 2008 at 10:40 am

    @will No bother!

  15. Evan Arredondo November 24, 2008 at 6:00 am

    Thank you a million times. The frustration has hopefully ended and I can proceed with my life. Evan

  16. BlueEvilTwin November 28, 2008 at 2:27 am

    all of these comments led to my successful running of reason adapted 3 for ox leopard thanks!!

  17. Nando89Castaneda December 10, 2008 at 10:11 pm

    i am having the same problem with mine.. but but when i browse my software the probeller head software is not there…. = / i already dragged the folder to my Hard Drive and installed it.. what can i do? is says failed to locate reason engine every time i try to open it.

  18. Wips December 25, 2008 at 6:05 am

    read/write worked for me but reason needs to be in applications folder…wont run from desktop etc…..

  19. themessenger January 2, 2009 at 12:21 am

    Thank you so much for this. I was like everyone else in here, working on my 100th bang on that wall…

    finally my computer is ready set go for some music production!

  20. Kevin January 10, 2009 at 12:54 am

    Wow, thank you man.

  21. mix master marx January 29, 2009 at 6:21 pm

    thank you soooo much for your help. i wouldn’t be able to make it without you

  22. mix master marx January 29, 2009 at 6:21 pm

    thank you soooo much for your help. i wouldn’t be able to make it without you

  23. Thejus88 February 1, 2009 at 7:08 pm

    Yes! It worked! Thank you(:

  24. greg February 27, 2009 at 11:16 pm

    worked like a charm. you da man!

  25. Ken McGuire March 1, 2009 at 3:37 pm

    @Svetlin, @greg No worries – you’re welcome 🙂

  26. 'ndrea March 1, 2009 at 9:43 pm

    thank’s a lot!!!

  27. George March 11, 2009 at 10:55 am

    Hey, it worked! Fantastic, thank you very much.

    To Nando89Castaneda – Sounds silly, but make sure you’re going straight from…

    Mac HD -> Library->Application Support etc etc.

    I was trying to go from

    My Home(George)->Library->Application Support etc etc… And not finding the relevant folders.

  28. Devin March 24, 2009 at 11:17 am

    Thanks a lot man, saved me a nice long phone call.

  29. Luke April 9, 2009 at 7:41 pm

    Thanks a ton! Worked flawlessly.

  30. Shelly April 27, 2009 at 6:11 pm

    Thank you! thank you! thank you! I got frustrated 2 months ago and left it until now, basically because I’m getting a new keyboard.

    This info is incredibly precious so much so that I raised my hands in the air and gave myself a high-five, one for me and one for you!

  31. tim July 27, 2009 at 6:16 am

    like everyone else here, you have completely made my day:)

    thanks so much

  32. bob August 21, 2009 at 8:34 pm

    just spent a hour trying to figure this out, then googled the error message and found this, now its working. Magic! Many Thanks.

  33. Nick December 12, 2009 at 5:44 am

    . Awesome! Thanks so much. P.S. I think you should put a PayPal Donate Now button on your site

  34. Ken McGuire December 17, 2009 at 1:38 pm

    Hey Nick, I’ll keep that in mind 🙂

  35. Jon Wootten January 14, 2010 at 4:04 am

    Thanks a bunch!!!

  36. songming August 28, 2010 at 6:01 am

    you did very perfect work. thank you!

  37. guitaristdan76 February 7, 2011 at 2:09 pm

    Thank you sooooo much for your valuable information. Now I got my Reason 3.0.5 working on my Mac…. God bless you….

  38. Jonathan Benjamin November 5, 2013 at 2:58 am

    it still say’s it on mines for some odd reason and i did exactly what the directions said

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