When attempting to simulate or compile a PLD file on WinCupl, I get the error:

Error '35602':

Key is not unique in collection.

after which the program crashes and closes.

What is the meaning of an error like this? A quick search brings up many questions (e.g., this, this, or this), but these all yield application-specific solutions. My scenario is also application-specific, but WinCupl is an old program and I can't find similar support online.

Some of the answers to those questions say something along the lines of: "This problem is caused by a key in a table of the database that is not unique." Can someone give some insight on what this means, and/or possible solutions to look into?

Note: I was thinking about posting on Electronics Stack Exchange, but this program doesn't seem to be commonly asked about on that site and I thought I might get a better understanding of the error here. If you think a different Stack Exchange site is better suited for this question, please flag/comment.

2 Answers 2


I had the same same problem and traced it back to a point where the tree in the project window is populated . I was able to work around it unticking Project under View on the Menu before compiling. Not sure if this will work for you but I spent hours looking for a solution to this so figured I'd share my experience.


I understand that some time has passed since the question was created, but I hope this will help someone else. I have the same error, but it occurred when I just opened the project. And so, as I discovered, the reason was the same file name (I copied the project file before some test changes to same-filename.pld.store). For some reason I had to close the project and WinCUPL, and when I tried to open it again, I got this error. The first thing that helped was to move the project file to another location. It opened normally. And then I moved the copy file to another location, and returned the project file back. And it opened normally again. Returning a copy to the old location and the project returns an error again.

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