Description
This warning appears when emake is unable to delete a backing store, a temporary directory created to hold output and intermediate files used by the build before they are committed to their final location. The specific cause of the failure is given by operating system error text at the end of the message.
Note that there are two forms of this warning. The first, “remove stale backing store dirs failed”, occurs when emake is unable to delete backing store directories left behind by previous emake invocations that terminated abnormally, without deleting their own backing stores. The second, “Couldn’t remove backing store”, occurs when emake is unable to delete its own backing store.
Reasons
The specific cause of the failure is given by the operating system error text at the end of the message. For example, the warning “remove stale backing store dirs failed: Unable to remove dir [path]: Operation not permitted” indicates that the user that invoked emake does not have permission to remove a stale backing store directory, perhaps because it was created by a different user.
Fixes
The correct fix for the warning depends on the specific failure. For example, if the specific message was “remove stale backing store dirs failed: Unable to remove dir [path]: Operation not permitted”, then the fix is to have an administrator or the owner of the named path delete the directory.