Skylight shines through blocks

Confirmed for 19w08a

Another situation is indoor is bright and outdoor is dark,(skylight exchanged between indoor and outdoor)

I believe this is why I can't turn off my villager breeder – the doors still see the sky no matter what.

Yup  I have had this same problem with my mob spawner!! Even when it’s pitch black outside there is still plenty of light inside the spawner 

Confirmed for 19w09a, MC-139446 has been fixed, abnormal skylight won't be created in 19w09a by running /fill command, but existed abnormal skylight didn't be removed(included created by running /fill command and created by rejoining the game)

Have the same problem. This destroys my villager crop farm as that relies on low light levels for the crops to break so that they can be collected by a minecart hopper

Confirmed for 19w11a

Confirmed for 19w11b

It seems like certain chunks reset their sky light to 15 when reloading the world. (The shadow seam is exactly at a chunk border) I can remove the sky light by filling the empty space and removing it again, but the sky light reappers after a while when I reload the game a few times. However it seems it's always the same chunks that are effected

Confirmed for 19w12a

Confirmed for 19w12b

Confirmed for 19w03a

Confirmed for 19w13b

I don't know about you, but for me a chunk keep having full sky light, and some chunks keep reseting to light level zero, even with torches and lava. I'm no expert, but may this all be related with a light miscalculation based of the chunk coordinate?

What I've noticed is that it seems that in certain chunks (always the same for that seed), the light of each block of that chunk always changes to level 15 when restarting the world, no matter how dark a room should be.

The bug is easily reproduced by creating a large empty room that is contained or intercepts the edges of a "light bugged chunk". Even if the room is completely closed and there are no light sources, the blocks contained in the this "light bugged chunk" will have skylight = 15. It seems that between 30 to 40% of all chunks are "light bugged chunk".

To quickly reproduce the error you can use the command below by creating an empty room at the coordinates x = 100, z = 100.

/fill 100 100 100 120 120 120 cobblestone outline

Enter this room without any lighting and restart the world. If the room intercepts any of these "light bugged chunk", upon restarting  all blocks of that chunk will be illuminated with skylight=15 (sometimes it is necessary to restart more than once). Note that this lighting is not just a "visual" bug, it avoids spawning of mobs.

Due to the high incidence of these "light bugged chunk", chances are great to be able to reproduce the error on the first attempt.

PS.: I have not yet encountered inverse situations where the environment is dark no matter how much it is lit by torches or other sources of light. However I have read other issues here about this.

The light system has been rewritten to version 1.14 and this bug is in all the latest snapshots. I believe it will be the last big bug solved before the pre-release version.

Confirmed for 19w14a

so far I was unable to reproduce this in a new world. Has anyone managed to do this? If not, it might have to do with certain chunks becoming corrupted in a previous version.

What I tried to do is to create a custom superflat world where I replaced the dirt layer with air, while keeping the grass above it. However there was not a single "light chunk" below the grass layer even after reloading. Everything was pitch black as expected

To confirm the bug, I tested it on a newly created world on 19w14a.

However, I had the impression that on this snapshot took a little longer to reproduce the bug. I had to restart a few times doing some actions among the restarts, like putting a torch inside the room, removing and replacing blocks from the ceiling, moving around the room, among other things. Only then could I reproduce the error.

But it did not take long, around 5/10 min and 3/4 restarts the error was reproduced as shown in the image I posted.

Confirmed for 19w14b

Is this bug really fixed? I've been using structure blocks in an end biome superflat for couple weeks and had this issue constantly. All the spawners weren't working, and mobs were burning in rooms. 

This still hasn't been fixed for me. I found some areas that needed block update though, but when I did that, it lighted up the room instead of darkening it.

All my weird lighting issues are now gone, this fixed it for me. If you are having problems getting this fix to register on your world you need to run the world optimizer. select world -> edit -> optimize world.

All errors related to this issue that I simulated in worlds created in snapshots prior to Pre Release 1 have been resolved after using the "Word Optimizer" feature provided in this Release.

When creating a NEW world, I can no longer reproduce the error. It looks like what the bug has solved.
 

Not sure why this is labeled "Fixed", but it seems that this bug still exists in 1.14.1 pre 2, as shown in the screenshots.

Xingye Zhang, Two Questions: The world that you found the bug was created in which version? If it was created in previous versions, did you use "Word Optimizer" feature provided in load game screen?

Please follow the steps mentioned in the "Mod Notice" above before claiming that this issue has not been fixed.

The world was created in snapshot 1.14 pre 1, and yes, I use "--forceUpgrade --eraseCache" option every time when I update/restart my server.

Skylight shining through blocks and light sources not working are happening at the same time, forcing me to switch the difficulty to peaceful.

@unknown, your issue is MC-149518.

Thanks for pointing that out. I just went to check that out, but I'm still quite confused with the difference between these two bugs...

This ticket: There's light appearing under blocks without any light sources nearby
MC-149518: There's no light appearing where there are light sources nearby

I think that you are talking about MC-142134, in which no light appearing around light sources.

In MC-149518, everything described there seems to be identical to this ticket.

And there are two issues shown in my screenshot: on the right-hand side, no light is appearing around light sources, which is reported in MC-142134; on the left-hand side, skylight is shining through the concrete roof, as shown in the F3 screen, which matchs the description of both this ticket and MC-149518, I think.

Whoops, yes, you're correct. My bad.

The issue described in this ticket was fixed in 1.14-pre1, but re-appeared later and therefore MC-149518 has been created.
The other issue (MC-142134) is similar, but not the same.