JavaScript error creating Custom Parts

I can’t create a custom symbol because every time the cursor is over a primitive the message “unsafejavascriptvoid(0)” pops up in the lower left corner of the window.

@jim_taylor0 - Could you share a screenshot which includes the error and what you have created for a symbol so far?


This is as far as I get. Anytime I select an element, the error pops up. Is it because I’m running Win7? Am I missing an update?


Hi Jim,
What browser are you using? Also, can you provide your user ID or project name so the Scheme-it team can evaluate further?

The project is called Oquirrh Reverb.

I’m using FireFox 77.0.1

My user ID is jim_taylor0

I get the same error using the Opera browser and Chrome

@jim_taylor0 - Unfortunately our team was not able to replicate the error you are seeing. You may need to dig into your local system/settings for a solution.

Is there any way for you to trace execution of JavaScript on my machine? The problem occurs as soon as I click on Builde a Symbol; the Symbol Editor comes up withthe error showing.

Unfortunately that information is not logged. Are you able to try another PC?

I just dug out my old laptop, installed a fresh copy of Firefox, and tried it. The moment I clicked on Buil symbols I got th unsafe:javascript error.

The laptop was running Firefox 65, is mnow running 77. I couldn’t try it with the old firefox because my profile on the laptop was corrupted. I’m going to get my son to try it on a machine not associated with any of mine.

Our team has continued trying to replicate this error with no luck.
This could be an issue with anti-virus software, browser extensions, or something else blocking JavaScript. Opening the console window in Chrome may help narrow down the issue. When you see the issue, press F12 and select the “console” tab.

Here is a screen capture of the result. Lots of errors. It may be time, at last, to upgrade to Win10. My son tried to get the error, but he couldn’t reproduce it either. He’s running Win10 and love it.

SchemeIt Error Tracking.docx (156 KB)

I updated my laptop to Win10 and got the same error. Reading the output from the F12 / console thingy, it looks like there is a bunch of data stored in the form of cookies that is making a mess. I tried clearing cookies in Firefox, but after clearing, some persist, even through a restart, for some reason. I will try the firefox folks, and then microsoft. Both my machines act the same, one with Win7 and one with Win10.

What puzzles me is that build a symbol worked tyhe first time I tried it, but then something broke, and it hasn’t worked since.

Going through the console printout again, it looks like the problem is in “” When I first click on build, I get a screen full of stuff about cookies, then stuff about various javascript functions, and finally a crash with error 403. If I close the symbol editor and hit build again, I don’t get all the junk, just another 403 error message. Each subsequent attempt gives the same message.

The printout also referred to things it didn’t like in:



Is some necessary resource missing from both my machines?

I’m so confused!

I created a new user ID uning my wife’s email address. I fired up Chrome and ran Scheme-It. Crreated a custom part, a 5U4GB rectifier tube, and saved it to my library. Got out of everything, tried again with Firefox. No joy. Went back to Chrome, tried the Build a Symbol button. The familiar error appeared. Picked up a 5U4GB from my library and put it in my drawing. Tried to Build a Symbol. Worked like a champ!

Scheme-It in Firefox hates me, whether I’m myself or my wife. Chrome loves me either way, after giving me the error message once.

I wish I could put a custom symbol in my project using Firefox, so I could see if the same magic works there.

This one appears to be fixed, possibly by magic. I still see the error when openoing the symbol editor, but only once. After that the editor works as it should.

One problem remains: I edited my custom symbol and saved it. The Symbol Editor shows it as it should be. My project schematic shows it with the original error, and I can’t change it.