I am a site/subsite owner with no rights at the site collection level. While creating a new subsite, I accidently removed  most groups from site permissions for the top level site I control.  As sometimes happens, rather than taking a few minutes to breathe, I thought to reverse my mistake by clicking on the Inherit Permissions button on the top level I own. The permissions were then the same as the site collection level. 

Below my top level site, called "TOP", I have 10 subsites which had unique permissions. Inheritance has long been broken from TOP and there are also hundreds of unique library and list group assignments (these were not inheriting either).

When I clicked that button on TOP, not only did TOP revert to collection permissions, every subsite, every library and list, reverted to the permissions granted at the site collection level as well except for 2 subsites where I did not have access. (lots of repair work to be done now) 3 custom permission levels, 2 of which I did NOT create, disappeared.

My understanding of breaking inheritance is that once broken, changes made above the break will not flow down. I would think that clicking on Inherit Permissions on the site above the break would have the same effect. The reversion would stop where inheritance was already broken.

Is my understanding incorrect or did we have some type of issue behind the scenes that caused this to happen?

Thanks!

yes if you have for example Site1 under the root site collection and Site2 under Site1 and you break the permission of Site 1 then Site 2 will not take sturcture of permission from Site 1 and Site 2 will be like the Root Site [Site Collection]

Fadi,

I'm not sure if your "yes" means I am incorrect or that we have something corrupted.

I would like to add that along with the complete re-inherit  and permissions removal waterfall effect throughout the multiple subsites, libraries and lists, custom permission levels were deleted. We had 3 custom permission levels, 2 of which the farm administrator had done and 1 of which was done by me. When I discovered they were gone, I went to add them back and found that my top level site was locked in an inherit state for permission levels and was not able to add or change any levels.  Nor can the farm administrator.

Anyone else who could contribute to this thread?  We're trying to find root cause and I'd like to get a definitive statement as to whether or not selecting Inherit Permissions from the top site level should cause all subsites/lists/libraries/bascially everything with unique permissions up to 6 layers down to inherit from the site collection again.

Thanks for your input!!!

I recently had this same thing happen.  If anyone has an explanation it would be greatly appreciated.