Ender dragon does not spawn if render distance is set to 10 or below

Confirmed. The exit portal doesn't generate either.

Uh, found a weird glitch regarding this report, placing an ender crystal on either obsidian or bedrock creates an exit portal

That isn't a glitch
If no exit portal fountain isn't there when you first upgrade to later mc versions or load the end and you place a end crystal near 0 0 it'll load in one

Is it possible, that the enderdragon appears when updating the game, without doing anything else ?

If not I would pretend as if there just is no Dragon in my world.

I just made a brand new world in 18w48b and while its true initially there is no enderdragon spawned in or the bedrock platform, once i got to 0,0 they both magically appeared//loaded for me

It might be the render distance you've set, see MC-140808 which was just resolved as Duplicate of this bugpost here.

The workaround with render distance 11 is not completely correct.

After some more testing, it seems like there needs to be an area loaded around 0,0.

If you are farther away, you have to set your render distance accordingly, e.g. a render distance of 11 will spawn portal and dragon if you're about 32 blocks away from 0/0, at render distance 10 it will spawn when you're about 16 blocks away of 0/0.

On higher renderdistances you might not have to be as close, but it should be noted that render distance and position matter.

E.g. if you set your render distance to 16 when you have been farther away/outside from the island, e.g. at X or Z = ~<256, it will not spawn the dragon when you reach 256 (16x16), but will spawn the dragon not until you are 7 chunks away from 0/0 (at 112 blocks from 0/0).

So it seems reasonable to currently assume that a certain area around 0/0 has to be loaded.

Also see MC-140853.

Please upgrade the summary on "Ender dragon and exit portal does not spawn when render distance is set to 10 or bellow". And also upgrade the description.

Confirmed Pierrot's comment. I normally play at a view/render distance of 10 chunks. After setting it to 12 chunks, the Ender Dragon spawns as expected, and it is therefore no longer necessary to go to 0 ~ 0 (or near) to cause it to spawn.

Well, this is an awful bug

As an easy fix, just pre-generate the End island by entering it at coordinates 0 ~ 0. For instance, run

execute in the_end run tp 0 100 0

then wait for the chunks to load, then get back to the Overworld (execute in overworld), then you can finally enter the End in survival and the dragon will be waiting for you.
Alternatively, if you have already generated the End wrongly, just delete the region files in your folder DIM1 and start the pre-generated workaround process as described above.
(You need to have op commands, but for testing snapshots, at least one player per world should always have op, as it helps you troubleshooting and fixing stuff).

I did notice it aswell, but with the Render Distance 11 or higher as you said, it will spawn.

If the distance is less than 11 Chunks, there won't be any mobs, not just the dragon.

Bob, when playing at a render distance of 10, I had plenty of mobs. The only mob that was not spawning was the ender dragon, unless I travelled near 0 ~ 0 in the End. Setting render  distance to 12 eliminated that necessity.