first its good to know the mod(s) in question...

I do know the mods. For example, I want to use the car,

PC&C Extended View Caboose

I subscribed to it. But, it says that I need,

Caboose Pack

So, I subscribed to that as well. I am looking at my Subscriptions page and see that both items are subscribed to. They both have check marks.

But, when I run the game, I grab the PC&C Extended View Caboose and it says,

"Quick Base Mod not found. Extended_View_Caboose_35855"

quote from the caboose pack comments

"Turns out the issue is that since this original mod was converted into the new modding system and updated to replace the original "egacy quickMod" version, and old liveries that required the QuickMod version do not work on the new version.
When a mod is created with the new system, it is basically a brand new mod with a new name and format.
So any liveries (legacyLiveries) that are based on the old QuickMod version of the train will not work with the new one.

What should have been done is that the uploader should have made a new workshop item for the new converted train mod in the new format (and kept the original legacy QuickMod version on the workshop so those old liveries can use it)."

Thanks for the reply. I guess I didn't read all the comments in the Caboose section. So, does that mean that I am just out of luck ever getting that caboose to work?

I have a list of other engines and cars that don't seem to work, probably for similar reasons. Are they toast also? I hate to lose so many great pieces of work.

Should these items be removed from the Workshop if they don't work anymore?

They should be removed, but at the same time, And this problem occurs with me too.

Originally posted by Bing987:

Thanks for the reply. I guess I didn't read all the comments in the Caboose section. So, does that mean that I am just out of luck ever getting that caboose to work?

I have a list of other engines and cars that don't seem to work, probably for similar reasons. Are they toast also? I hate to lose so many great pieces of work.

Should these items be removed from the Workshop if they don't work anymore?

Technically it's also possible for you to set up the livery yourself to work with the updated version of the mod (as long as they didn't change the UV map when updating it, which is rather unlikely in this case) by copying the texture file to your Custom Assets folder and then setting it up in-game like any other Train Mod Livery (there's a guide in the Guides section with more details on that part).