Resume from hibernate fails sometimes

Hello all,
on my machine (ThinkPad E545), hibernate & resume sometimes works perfectly, but sometimes (i.e., more often) it fails with a “signature verifying” error.

After removing “splash=silent quiet” from the grub kernel parameters, I can see some messages from PM during resume (BTW: Is there a logfile where I could find these messages later on, too?):

Image loading seems to work, there are messages saying:
PM: Image loading progress: 0%
PM: Image loading progress: 100%

But then:
PM: Signature verifying failed: -19
PM: Bypass verification on non-EFI machine

And then, the machine is just dead. I can only switch it off the hard way.

Any ideas? If you need more information, just let me know.

perhaps someone else can diagnose your problem more specifically, but i had the same random failures on resume. Investigations suggested this is a general linux problem going back many years. I now only use suspend to RAM which works extremely well (negligible battery drain).

Yes, hibernate has always been kind of a game of chance. And yes, suspend to RAM doesn’t make problems.
But it worked fine for me with Leap 42.1, so – in theory – it should work with 42.2, too.

I’d be happy for any hint that could help me to at least understand the problem.

What exactly do these messages tell me? Is “-19” an error code? Does it mean something?
How and where is the hibernate/resume process configured? Can I produce a more detailed debug output? Logfiles?
What has changed regarding hibernate/resume between 42.1 and 42.2?
Anything I could start with?