"You Cannot Reverse" Warning

[tmurphy1020]

"You cannot reverse this change with the Edit > Undo command. Do you want to continue anyway? (Yes, No) every time I open InDesign now, this window pops up. It comes up again when (at a minimum) the first document is opened. There is nothing I am trying to undo. Any insight as to where this is coming from or how to fix it?

[leo.r]

Check your Startup Scripts folder:

<InDesign folder>/Scripts/startup scripts

Is it possible there are scripts there that do something upon InDesign launch or document opening?

[Barb Binder]

Hi @tmurphy1020:

This message seems to be related to exceeding InDesign's undo history or RAM capacity. You haven't done anything on open, so unless you uncover a complex start-up script causing the issue before you start working, let's focus on RAM.

InDesign requires 8GB of RAM (16GB recommended)—how much do you have? Does restarting your computer and only opening InDesign bypass the message? 

If no to all of the above, the next think I would try is rebuilding cache/preferences.

~Barb

[tmurphy1020]

I have 8 GB of RAM. When opening ONLY InDesign after a restart, I still get the message.
TPM

[leo.r]

I have 8 GB of RAM. When opening ONLY InDesign after a restart, I still get the message.
By @tmurphy1020

I hope the reset suggested by @Barb Binder helps (at least temporarily). But I also think the low memory issue mentioned by Barb contributes to your problem. While 8 GB RAM is officially supported, in reality it's barely sufficient to keep InDesign afloat. (Plus the amount of free space on your startup drive also matters).

I know you're on Mac so depending on the model you may still be able to add memory (if your Mac is about 6 years old or older). Otherwise, the only way to increase memory is to replace your machine with one with a higher amount of RAM installed.

[Barb Binder]

Then the next thing I would try is rebuilding cache and preferences. 
https://www.rockymountaintraining.com/adobe-indesign-rebuilding-preferences-cache/

~Barb 

[Manan Joshi]

Did you install any 3rd party plugin or script off late? This seems like a code is executing and it is failing. So if you have any such thing installed remove it. Did you follow the instructions given by @leo.r? That should take care of the scripts. For plugins you would have to check the Plug-ins folder inside the InDesign installation directory. There could be other things like CEP extension etc. We will check for those when you tell us more about this troubleshooting

-Manan