Strange error - SL3, LMS

I am experiencing a very weird error:

In a quiz, when advancing to a certain slide, I get this error:

This is what the console tells me:

app.min.js:31 Uncaught TypeError: Cannot read property 'toString' of undefined
at m (app.min.js:31)
at s (app.min.js:1)
at D.n.getEncodedString (app.min.js:31)
at D.n.getEncodedValue (app.min.js:31)
at D.n.encodeVariable (app.min.js:31)
at Array.reduce (<anonymous>)
at D.n.getResumeData (app.min.js:31)
at D.n.meetConditionOrReturn (app.min.js:31)
at D.n.s [as getResumeDataOrReturn] (app.min.js:1)
at Object.collectResumeData (app.min.js:20)
11 Replies
Jeff Forrer

Any update on this?  I have the exact same error after performing a JS call, and then clicking the BACK button in a SL3 course (not with latest update as I have had other issues with that update so reverted). 

Never fails in SCORMCloud, fails everytime in Cornerstone LMS.  Published as HTML5, SCORM2004 vs 3.

Thank you.

Uta von stebut

Hi, I've got the same error : app.min.js:3 Uncaught TypeError: Cannot read property 'toString'

I think the LMS is sending a variable undefined instead of empty string. How can I do to inspect which variable is impacted? It would be easy adding console logs if I had a not minimize file but I just have a app_min.js that I can not read...

Does someone have a solution? or news?

Uta von stebut


I'm not using Cornerstone and I think the LMS providers won't change anything to their LMS.
I think the LMS is sending an undefined variable instead of empty string and the storyline blocks against that..
Is it the reason to your mind?


Uta von Stebut
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Ashley Terwilliger-Pollard

Hi Uta,

If you're trying to use some JS to call those variables from your LMS into Storyline, that's something I'll have to defer to the community for as well as it's a bit over my head, and not something we offer support on.

It looks like Jeff may be able to help you when he returns to his office! 

Also, it looks like your email signature came through when you replied via email. You can remove that if needed by clicking ‘Edit’ beneath your response. Here’s a quick Peek video if you need help.

Chris Vostmyer

Just wanted to update the status on this. Jeff's issue was caused by a JS error.

JS was written to pull the learner name from the LMS and inject it into Storyline as both a first and last name.

SCORM Cloud gives the learner name as Last Name, First Name, but Cornerstone give the learner name as First Name Last Name. 

The code was written for SCORM Cloud so it parsed the string with a ", ". When it was moved to Cornerstone, there was no ", " in the name so the first name was undefined and the last name was the full name.

Storyline tries to save its state when leaving the slide, to do that it serializes variables but doesn't check if a variable is undefined. This giving you the error of "Cannot read property 'toString' of undefined".

If you see an error like this, and are using JS to send variables into Storyline, check to make sure that they are not sending in undefined values.