Hi ! I got the same error screen. I got the sample project specifically because I was getting an error regarding the Timer plugin in my own game, saying "Cannot read property 'getHexOrName' of undefined". So, to see what the timer looks like in a game without issues, I got the sample project, which threw me the str.replaceAll issue. But then, I tried cancelling all plugins other than Book, the Sample Project one, and the Timer, to focus on just what brought me here. But now, I'm getting THIS error screen. Any idea what's going on? I'm lost ;-;. This error screen could be my fault, but then why did I get the "str.replaceAll" one? I don't now, would love your help, thank you so much.
Viewing post in Weird message during playtest
Hi there!
Your Project
That error you got on your game: "Cannot read property 'getHexOrName' of undefined" it's because one of those things:
- missing EliMZ_Book
- EliMZ_Book is outdated
- EliMZ_Book is not above the EliMZ_Timer
- Some plugin parameter on EliMZ_Book is bad configurated triggering a silent error and failing to load the EliMZ_Book, resulting in Eli.ColorManager being undefined.
Try to check those things and see if the problem is solved.
My Sample Project
That is a little trick. Because I never managed to replicate the str.replaceAll issue. It seems that I also forgot to answer the OP Team Dream Treasure to try to check on this =/ The screenshot he sent me was not the one I asked, so even now I don't have what I need to investigate that.
Now, I just did the following:
Attempt 1
- Downloaded the Sample Project from the itch io page.
- On the first map I just hit playtest, it runs normally no error.
Attempt 2
- I disabled all the plugins, and just turned ON EliMZ_Book and EliMZ_Timer. Worked just fine, no errors.
Attempt 3
- I updated the EliMZ_Book and EliMZ_Timer, downloading that plugins from their itch io page, and put them on the js folder of the sample project.
- Open both their plugin parameters to make sure they also updated and nothing is wrong there
- Hit playtest, no errors at all.
Continuing...
Now, the error showing on your screenshot is "Cannot read property 'clamp' of undefined, on the line 3724 of the rmmz_core.js file. Which is this line on the core versions 1.9.0 that the sample project have:

Now, some backSprite is trying to set it's alpha value. And that value is undefined. Following the stack trace, it seems that the Window_TitleCommand is what is trying to set the backOpacity value and that value is undefined. i really don't know why this is happening.
I'm not managing to trigger the error again, so i don't know what is wrong. The Sample Project is a little outdated... Maybe you can try to update the RPG Maker Core files and EliMZ_Book and EliMZ_Timer to the latest versions.
But you need to tell me exactly your steps. Because that updated error screen is from the last updated version of EliMZ_Book, but the sample project does not have that EliMZ_Book version by default. So you just copy and pasted an updated version there? What exactly was your steps?