João de Camões

The issue can be closed - it's caused by the 1.17 OptiFine Preview, and does not occur with Vanilla 1.17.

The same problem also occurs with bundled Java.

OK, I reset the Java parameters to default and now it at least starts with the bundled Java.

It still happens on both 1.14.4 stable and 19w37a.

Does anyone have a solution for the issue? I deliberately left those chunk on my world in such a state, for a specific reason. You don't expect me to manually walk through the whole world in an older version to populate every chunk, do you?

Another screenshot of the good one, from the same angle as the bad one:

Two screenshot are attached: the first one shows the way the building is suppose to look like (I reused the design so I have buildings with it that are unaffected by the dark patches), the second is the building with the dark patches. The patches only really appear at night, during day they are not really visible.

I'll upload a cut down version of my world, but it's easy to reproduce:
1. Fix the glitch by loading the world with force upgrade and erase cache;
2. Log in, go to the chunk for the first time - it will look fine;

3. Go far away and then back, dark patches will reappear, eg. on the primarine railway station.

And every time the chunk is unloaded and loaded again, the patches increase in quantity.

The same thing still happens on 1.14.2 final.

Unfortunately, I still had the problem on 1.14.2 pre-release 4, even after using force upgrade and erase cache on the world. Each chunk was fine on first load, but after unloading it and loading it again (done by moving far from the location and then back), the darkness patches were back.

I confirm this, and it's even worse when Unicode font is set.

I have this, on a world that was previously opened in both 19w14b and 1.14-pre1 (the world goes all the way back to Beta 1.3_01 and was fine until the 1.13 snapshots when problem started, that still persist even in 1.14-pre2), and in addition I've also seen random chunks get entirely regenerated.

Screenshot of the issue in Pre-Release 2 attached.

I just had the issue in Pre-Release 2 (but it might have occurred in Pre-Release 1 already).

OK, MC-142134 is about the dark patches. But what about the regeneratign chunks? That reminds me of another issue that exited last year but was then resolved. Basically, some chunks that were fine in 19w14b, have now been completely regenerated.

Looks like my issue is a duplicate of this (may want to merge them), and my blast furnaces were placed in either 19w08b or 19w09a.

I confirm this issue - whenever a minecart reaches a curved rail, it bounces back or sometimes goes completely out of place (had minecarts on an upper floor of a building end up on the floor below after being bounced back at a curved rail, for example).

Right now, I saw a chunk load fine in front of me, and then get regenerated.

Based on what I have observed, any chunks that were last opened in anything earlier than 1.13 final, seem to get regenned or at least messed up by 18w44a/18w45a. Any chunk opened in 1.13 final or later, will not get regenned or messed up.

By the way, this has been happening since some point during Beta 1.13 snapshots. I've even seen it happen to my 1.12 creative world - most of the town at spawn would get almost erased and replaced with wilderness.

Now, both of the affected world eventually had customization options added to their level.dat, so there might be that stuff in the chunks, but I removed that stuff from the level.dat (or else I couldn't even convert the world at all), and I would expect that if there's customization data in the chunks, the game would simply ignore that data, not decided to mess up the chunks.