I was getting the same errors, i.e:
invoke-rc.d: initscript acpid, action "start" failed.
dpkg: error processing acpid (--configure):
subprocess post-installation script returned error exit status 1
Then I rebuilt acpid from the source package, and it installed without difficulties. After that, I cannot recreate this bug at all, even if I downgrade to acpid_1.0.4-5ubuntu6 or acpid_1.0.4-5ubuntu7 and try to upgrade again.
I was getting the same errors, i.e:
invoke-rc.d: initscript acpid, action "start" failed.
dpkg: error processing acpid (--configure):
subprocess post-installation script returned error exit status 1
Then I rebuilt acpid from the source package, and it installed without difficulties. After that, I cannot recreate this bug at all, even if I downgrade to acpid_1. 0.4-5ubuntu6 or acpid_1. 0.4-5ubuntu7 and try to upgrade again.