* UPDATED NOV-19-2019 *
*** GREAT NEWS ***
This workflow also works with reverting Adobe CC 2020 (ver 14.0) projects back to Adobe CC 2019 (ver 13.0) software. Some of the information in this wiki will look a bit different, but you'll totally figure it out! 
Just follow the steps below!!
So...it happened! The latest and greatest version of Adobe Creative Cloud Suite was released earlier this month (October 15th, 2018.)
This new Adobe 2019 Creative Cloud Suite is chalk full of new and exciting features and improvements. For a detailed list of these updates more information can be found at the link below:
https://www.adobe.com/products/premiere/features.html?mv=product&mv2=accc#
In this instance, we are focusing specifically on Adobe CC 2019 Premiere Pro (ver 13.0)
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| But....sometimes you'll need to work in other facilities...or collaborate with other professionals. If they are using an older version of the Adobe Creative Cloud Suite (like Adobe CC 2018 Premiere Pro ver 12.1.2) you may have gotten an awful error similar to this one when trying to open your project. |  Image Removed
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! DON'T PANIC !
Albeit, it's frustrating that Adobe does this, (especially because they unapologetically continue to take your money for the subscription,) There is a simple fix for this problem! Follow these easy steps:1.) Isolate your Adobe 2019 CC Premiere Pro (ver 13.0) project file. In this instance, I have saved a copy to my Desktop. Note I've given the name a description indicating the software version.
Here the file is named My-Adobe-PremierePro-Project_2019
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| | 2.) We should make another copy of this file...just to be on the safe side. The easiest way to do this is simply right-click on the file and select Duplicate. |  Image Removed
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3.) Now I have two copies of my Adobe 2019 CC Premiere Pro project file on my Desktop. To avoid confusion, I'll rename one of them to indicate I intend to use this version with an older version of Adobe Creative Cloud...specifically Adobe 2018 CC Premiere Pro (ver 12.1.2)
Here I've named one of them My-Adobe-PremierePro-Project_2018
 Image Removed | 4.) Navigate to the Applications folder located on the Macintosh HD. Scrolling alphabetically through the list, you will find a software called TextWrangler.
Double-click the TextWrangler icon to launch the application.
If you are working on your own computer, Textwrangler is Freeware and can be downloaded directly from the Developer. The Developer has also incorporated Textwrangler features into their Lite Version of BBEdit. More information can be found on their website.
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| | If you receive an error message like this one, simply click OK to ignore the error message. |  Image Removed
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5.) Once the application has loaded, we need to open a pathway to the file. Navigate to the application tool bar in the top of the screen and choose File → Open | 
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6.) In the pop-up window, navigate to the location where you saved/duplicated your Adobe Premiere Pro Project files and click Open.
In this instance, I have saved my files on my Desktop so I've selected Desktop in the pop-up window and clicked Open in the pop-up window.
Image Removed7.) TextWrangler loads the path or folder you opened. I can now see a list of files to preview in the left-hand column of the TextWrangler application Window. I can click on any file in that folder or path to preview its code.
Let's select the duplicate project file we renamed to My-Adobe-PremierePro-Project_2018 in the left-hand column of the TextWrangler application window.
Look closely at the Header information on the first few lines of the file in the right-hand column of the TextWrangler application window. This information dictates what the file is, where it comes from, and how it should be opened.
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| More specifically, look at Line 4
This is where Adobe is telling us the project was saved in a newer version.
In this case, the version is "36" which indicates the project file is only accessible with Adobe CC 2019 Premiere Pro (ver 13.0) and above.
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| 8.) Simply use your mouse to select the "36" with the cursor and change the number to "35"
"35" indicates the project file is accessible with Adobe CC 2018 Premiere Pro (ver 12.1.2) and above.
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| 9.) DON'T FORGET TO SAVE THE CHANGE YOU JUST MADE! Navigate to the application tool bar in the top of the screen and choose File → Save. |  Image Removed
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10.) VIOLA! Your duplicated, edited, hacked Adobe Premiere project file will now open normally in Adobe CC 2018 Premiere Pro (ver 12.1.2.) Thanks, Adobe! . xoxox .
Let either the Proctor or Technical Staff know if you're having difficulty with any of these steps.
Image RemovedAttempting to open a premiere project from a newer version in an older version, you will get this error. This is typically done to prevent project errors from new features that have been added between versions. If you haven't used any special effects or tools that were recently introduced, you should be fine, but proceed
with the understanding that your project may not work entirely as you expect. | Image Added |
Navigate to your premiere project and make a copy of it (so you have a backup just in case) |  Image Added
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Right click on one of the files and select rename
In the field, change ".prproj" to ".gz" |  Image Added
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| You will get prompted to make sure you want to change the file extension, click "Use .gz" |  Image Added
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Launch spotlight (either CMD + Spacebar or the spyglass icon on the top right of your screen) and search for
terminal, then launch it |  Image Added
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| In the terminal window, type "cd" and then press space |  Image Added
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In the finder window where you have your premiere projects, click on the folder icon at the top and drag it into
the terminal window. Release once the plus sign appears on the folder.
The path to the folder will be pasted into
the terminal Afterwards, press enter |  Image Added
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You are now in the folder with your project Type 'gzip -d projectname.gz' (projectname being your projects file name) You can type the first few letters and then press the tab key to auto complete the name up
to the extension, then add ".gz"
#Note: If you have a space in the filename, you will need to add a "\" (backslash) before the space, like this
"test\ copy.gz" Once done, press enter |  Image Added
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In the finder window, you will notice now that the ".gz" has been removed from the file. Now right click on it and select Open With > TextEdit |  Image Added
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A window will open with a bunch of text Count down to the 4th line It'll look something like this
(<Project ObjectID="1" ClassID="62ad66dd-0dcd-42da-a660-6d8fbde94876" Version="39">)
Change the number after "Version" to 1 so that line looks something like this now
(<Project ObjectID="1" ClassID="62ad66dd-0dcd-42da-a660-6d8fbde94876" Version="1">)
Afterwards, press CMD + S or go to file > save |  Image Added
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Return to the terminal window and type 'gzip filename' (filename being your filename #WITHOUT AN EXTENSION#) Then press enter |  Image Added
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You should now see the '.gz' extension again Repeat the above steps to rename it from '.gz' to '.prproj'
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Once you have renamed the file back to .prproj, open the project in premiere.
You should get prompted to upgrade the project, stating it was created in an older version of premiere Update the name / location as you see fit and press Ok. The project should now open and you can verify that everything seems to be as you had it on the other version of premiere |  Image Added
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