Serious Error in Cubase 11 Causing CPR Corruption and Un-Openable Sessions

If you see picture attached^

Via auto-save, or via the creation of .baks or ‘back ups’, a serious error is making the .cpr file size as large as 4gbs. Once a session is over 2gbs it will no longer open and is un-usable. This is nothing to do with the ‘content’ contained within a session, this has happened a few times to me and there is no consistency between how many tracks/audio/plugins are in a session to when this error happens. The dramatic increase in file size is some corruption not caused by the user.

I am using windows, and use the same template (over a 1000 tracks) for each project and usually the file size never exceeds 250mbs.

Would anyone know what is causing this? Can’t find help anywhere online.

Hope you can help me!!!

Are you using Spectralayers?

No spectral layers installed on the machine

Hi and welcome to the forum,

Do you use NI Kontakt?

Yes - several instances of both k5 and k6, however most tracks are midi tracks (connected to 2 VSL Machines)


Are NI Kontaks sitting in the VSL or in Cubase, please?

I have Kontakts loaded both locally as instrument tracks, and present in my VSL proejct.


There is known issue on Kontakt side. It eats unexpectedly large project size. It had been reported on both sides (Steinberg and NI) already.

Okay - it’s worth noting that it’s not to do with the amount of tracks, this happens when there is little or many local instaces of Kontakt. I have not had this problem with previous versions of Cubase. Also, the size increase will happen randomly, not after adding more instances of Kontakt for example.

I will look out for a solution as I have lost a great deal of work because of this.


This is interesting info, thank you.

This is the same for Sine player which I also have local instances of

Hi Martin,

Has there been any developments in this? Has the new Cubase 12 improved this at all?

We’re currently losing about 10% of our work because of this. Our short term work-around is to avoid having too many locally loaded instrument tracks/plugins (especially kontakt 6 and Sine Player) but this in incredibly limiting to our work flow.

Thank you


As far as I know, only NI can do something with it.

Do you have any links or solutions to send on here? Getting no luck online.

Would be very very grateful!!