Thinkpad T400. MATE Desktop and NetworkManager. I am testing 14.2 64-bit before updating all 14.1 systems.

When I invoke sleep by closing the lid and then open the lid, the system always returns to sleep. Pressing Fn causes the system to awaken and remain awake.

I can invoke sleep with Fn+F4 and awaken with Fn. No double sleep. I can press Fn+F4, close and then open the lid. No double sleep. Only when invoking sleep by closing the lid does the system return to sleep after opening the lid.

Same result with AC or battery, wired or wireless.

The behavior is repeatable. While confusing at first, after I thought I noticed the pattern I spent about 20 minutes trying different combinations. Only closing the lid causes the return to sleep.

The 14.2 test system is updated from a working 14.1 system. Thus all of the /etc/acpi and /etc/pm files were inherited from the 14.1 system. The 14.1 system never exhibited this odd behavior.

I have not tried a clean 14.2 install on the laptop. I don't really want to rebuild a new system from scratch with a clean install.

While a work-around is invoke sleep only with Fn+F4, the quirk is a mild nuisance.

Any ideas?

The problem was reported on the Thinkpad T400 here and arises from the interaction of the lid close and the lid open events with acpi scripts.
For other script suggestions see here. It is hard to be definitive as the particular hardware seems to be a factor.

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Thank you.

Using the links I discovered more than one thing changed from 14.1 to 14.2 with this anomaly. Not only are separate lid-open and lid closed event files needed, but the outputs of the special Fn+Fx hotkeys changed too. For example, Fn+F4 (sleep) changed from event=ibm/hotkey HKEY 00000080 00001004 to event=button/sleep SBTN 00000080 00000000 K.