Cannot connect to Photoshop on Mac
As your first point of action, please re-start your computer.
If the issue is still not resolved, then below are some reasons why ProSelect will give an error when trying to connect to Photoshop on a Mac:
Checking if ProSelect can connect to Photoshop
If you are not sure whether ProSelect is having a problem connecting to Photoshop then you can do the following:
In ProSelect 2016r1 and newer:
Use the Test Photoshop Connection button in ProSelect's Preferences -> General Settings -> General -> Photo Editor.
This will attempt to send a command and get a response from the default version of Photoshop (see "Multiple Copies of Photoshop Installed" section below). If Photoshop is not already running it will launch it. If you are using CC 2017, see this article: Photoshop CC2017 startup issue on Macs.
If the connection is working, the version number of Photoshop that ProSelect successfully connected to will be shown and it means that ProSelect is successfully able to communicate with Photoshop.
In this case, you should be able to use a Cmd-T (Open Original file in Photoshop) successfully. If the problem ONLY occurs when running Hi-Res Production, then you should check the Debugging Production Problems article.
If the above test does not work as described then check the solutions in the sections below.
In ProSelect 2015r3 and earlier:
Open ProSelect's Preferences and go to Image Effects -> Custom Effects Actions.
Then click the Reload button below the Photoshop's Actions list on the right side of the window. This will launch Photoshop if it is not already running. It will then get Photoshop to send it the names of all of its current actions.
This should only take a few seconds after Photoshop has started. When complete, you should see the action list updated AND the version of Photoshop and the current date shown next to the Reload button and it means that ProSelect is successfully able to communicate with Photoshop.
In this case, you should be able to use commands (Cmd-T) to like Open Original file in Photoshop. If the problem ONLY occurs when running Hi-Res Production, then you should check the Debugging Production Problems article.
If the above test does not work as described then check the solutions in the sections below.
Make sure Photoshop is not waiting for user input
When ProSelect sends a command to Photoshop it will not get a response from Photoshop if Photoshop is displaying any dialog boxes or message windows. In this case, after a short delay, ProSelect assumes that Photoshop is nor running and displays a message Cannot Connect to Photoshop.
Solution: Switch over to Photoshop and make sure that Photoshop is not displaying any Dialog boxes or windows and/or Start Photoshop manually and check that no message boxes appear.
Photoshop can stop in cases such as:
Getting rid of the Start Workspace window in CC 2015 on startup
This window is shown, by default, over the top of your work area when opening CC 2015 and will prevent ProSelect from sending commands to Photoshop. To prevent this open Photoshop's Preferences, select the General section on the left and uncheck the boxes next to both
Show "Start" Workspace When No Documents Are Open
The close and re-open CC 2015 to verify that this screen is no longer shown.
Getting rid of the Start Workspace window in CC 2017 on startup
Although it doesn't seem to effect ProSelect, many users don't like this feature. You can turn this off using Photoshop's Preferences -> General. Then uncheck Show "Start" Workspace When NO Documents are Open and Show"Recent Files" Workspace When Opening a File.
Checking the Debug Log
If you are getting an error message when you using Test Photoshop Connection button (in ProSelect 20161r and newer) or the Reload Photoshop's Action List (in ProSelect 2015r3 and earlier), then you should also check for error messages in ProSelect's Debug Window by following the instructions in this article: ProSelect Debug feature. After opening the Debug Window click the Reload Button check the messages. They should be something like this:
The version of Photoshop that ProSelect is trying to connect to is shown as indicated. If this is different to the version that you expect then see the section below "Multiple Copies of Photoshop installed".
It is possible that the script file has become locked (read-only) and ProSelect is unable to update it. You can delete this file ("photoshop_script.jsx") from the location shown and try again.
Shell script Timed out error
Some users who had recently upgraded to OSX 10.12 (Sierra) were seeing the error below multiple times:
Executing Script to find Photoshop count:1
86674.139354: Script ended
86674.139397: Shell script Timed out
The problem was due to a bug in the earlier releases of OSX 10.12. Upgrading their Operating System to the latest release fixed the problem.
Running Hi-Res Production on an item that takes more than 3 minutes to complete
If you are using ProSelect's Hi-Res Production to build a item that is either very large, has a large number of images in it and/or your computer is not very fast or low in memory, then you may see a Connect Connect to Photoshop message after about three minutes or so.
This is because ProSelect will automatically timeout if it doesn't get a "job completed" message from Photoshop before this time. In most cases, you will find that Photoshop will still complete the job and you will just have to manually re-start running Hi-Res production again from the next item.
Note: You can always switch over to Photoshop to check if it is running during this extended delay.
Apart from getting a faster computer or adding more memory to your computer, you may wish to run Hi-Res production on large complex images separately to ensure they complete. Then select all remaining smaller items and run these together.
Using OS X Mavericks or Yosemite
Due the changes in these versions of OS X, you may sometimes get a Cannot Connect to Photoshop error if your computer's memory is fully used. Trying again or re-starting your computer usually fixes this. However, we have also made changes to ProSelect to, in most cases, stop the occurrence of this problem.
These changes were incorporated into ProSelect versions 2014r1.10 and 2015r1.2 or newer. So if you are using these versions of OS X then best to update or upgrade to one of these newer versions.
Multiple Copies of Photoshop installed
(When using ProSelect 2010r1.6 and newer)
If you have more than one copy of Photoshop installed on your computer then check the following:
If Photoshop is not running the first time you do an action in ProSelect that requries connecting to Photoshop, ProSelect will tell OSX to launch Photoshop. This will usually be the latest version that you have installed. ProSelect remembers which version was launched and directs all future calls to that version only. So if you close that version of Photoshop and then open an other version, ProSelect won't be able to connect to it because it will be still looking for the first version.
Solution: Leave open the version of Photoshop that you wish to use. Then Quit and Re-start ProSelect. Because Photoshop is now already open, ProSelect will identify and use the version that is already running.
Checking that Photoshop can still run script files
In most cases, ProSelect communicates with Photoshop by telling it to run a script file. Sometimes, a fault in Photoshop can prevent it from running these files at all. To check this:
If this you don't see the above message, then you definitely have a problem with your Photoshop installation. You could try uninstalling and re-installing Photoshop. If these tests still do not work, then we recommend that you contact Adobe for support.
Using Third Party Plugins
One user found that Photoshop CC 2015/2017 (on a Mac) would only run scripts (see above section "Checking that Photoshop can still run script files") after he disabled his Photoshop plugins. This turned out to be due to a combination of using ProSelect 2016r1.9 and NIK/Google plugin. (See "Using ProSelect 2016r1.9 on Mac" below).
Since it is possible that other third-party plug-ins may cause similar issues in the future, we have included this information on testing Photoshop with plugins disabled below.
To disable Photoshop plug-ins, start Photoshop with Shift key and click the "Yes" button when it says "Skip loading optional and third-party plugins?". Then test the ProSelect connection to Photoshop again. If it now works, you may need to remove one or more third-party plug-ins or contact Adobe for support. This Adobe article may help: Photoshop plug-ins troubleshooting.
Using Photoshop CS5
Make sure that you have updated Photoshop to version 12.0.1 or later. The first release of CS5 has some bugs that break the connection with ProSelect.
Version Specific Issues
Using ProSelect 2016r1.9 (Mac version only)
This release included a change in the path separators in the Photoshop script files that ProSelect generates from ":" to a "/". This was done to solve an issue with Photoshop not being able to read and write from some NAS drives. (We suspect this is either a Photoshop and/or OSX bug). However, it was subsequently discovered that, any Photoshop scripts file with paths in this format would not work if you also have the NIK/Google plug-in installed in your copy of Photoshop.
As such, we have reverted the path separators back to ":" in the next update as more people have the NIK/Google plugin than the NAS drive and hopefully the NAS issue will be fixed by others in the near future.
If you are using ProSelect 2016r1.9, then please download and use ProSelect 2016r1.10 and newer.
Using ProSelect 2010r1.2 - 2011r1.9
Odd characters in the Startup Disk name
If you have single or double quote characters in the name of your startup disk, this will cause the script that connects to Photoshop to fail.
Examples of bad names include My iMac 17" disk or Fred's hard disk.
Solution: Rename your startup disk to a name without any quote characters.
This problem has been fixed in ProSelect 2011r2 and newer.
Using ProSelect 2010r1.2 - 2010r1.5
ProSelect version 2010r1.2 included some changes to allow it to work with Photoshop CS5.
We found that these changes can affect ProSelect's ability to connect to Photoshop if you have any double-quotes in the name of your startup disk or single or double quotes in your account name
eg Mac 17" Disk, Peter's Computer
These problems were fixed in ProSelect 2010r1.4 and newer.
We also found that the above changes prevented ProSelect connecting to Photoshop if you are using OSX 10.3 or 10.4. This error was fixed in 2010r1.6 and newer.