"Too many pairs created" error without any apparent reason

Hi everybody !

I've been working on a project for two years and the physics part has always been working perfectly.

However, since a week, I started having an error after playing 2-5 minutes : the message I get in the console is "Internal error: Too many pairs created, new pairs will be ignored. This is perhaps due to an excessive number of objects created at one location." Then, it starts ignoring some collisions, but not all.

When I check in the profiler, the number of collision is still the same (18.8k, which is normal I think). I can't understand why I start getting this error. I didn't backup the project so I can't go back.

Has someone already had this error ? What can be the cause if the number of objects or contacts doesn't increase ?

PS : I'm switching between Unity 4.6.4 and Unity 4.6.5 versions.

 

In this thread
http://answers.unity3d.com/questions/359835/internal-error-too-many-pairs-created-new-pairs-wi.html
someone answered saying its a physx limit. There are to many collisions happening at a single point in space. Maybe check to see if there is a bunch of objects somewhere colliding.

This post here
http://forum.unity3d.com/threads/on...airs-created-new-pairs-will-be-ignore.125451/
says their mesh collider was bad in some way, causing issues.

In this thread here
http://www.reddit.com/r/Unity3D/comments/2iqw3e/internal_error_too_many_pairs_created/
someone talked about having a large compound mesh for your geometry while not marking it as static.

 

Thank you for these links I had already seen the two first but as I said the number of collisions doesn't increase. I have no mesh collider triggers, and everything is marked as static, so unfortunately the causes doesn't seem to be the same.
In my case, happens when I instantiate cars (Rigidbody-2 colliders-4 wheel colliders) but it doesn't always happen so it's difficult to understand what are the causes.
If I can't solve it, does someone know if there's a way to catch this error ?

 

When I print, only one object is instantiated. How can only one collider cause this error ?
PS: I also get this error sometimes when I'm in Editor mode.