Inevitably after a large update to X-Plane like 11.30, new bugs go undetected during the beta process. We do a quick update to try to kill off these bugs as quickly as we can, e.g. X-Plane 11.11, 11.26, 11.31.

Yesterday we shipped 11.31. Unfortunately this isn’t the end of X-Plane 11.30 bugs, and in two cases, 11.31 appears to have introduced new problems.

We are working now on X-Plane 11.32, and our rough plan is:

  1. Fix all the really serious bugs (crashes, performance so bad you can’t fly) and ship that ASAP.
  2. Fix the rest of the lingering 11.30 bugs.
  3. Take a moment to question life choices.

If you are seeing crashes in X-Plane 11.30 or 11.31, the most useful thing you can do is to auto-report them, preferably with your email address in the report, so that we can contact you to run special builds.

The rest of this post is an update on the state of some of these bugs.

Driver Bugs

Older Intel OpenGL drivers contained a bug in their pre-processor that caused them to reject our HDR shadowing shaders. I rewrote the shaders to work around this bug for 11.31, and the rewrite has exposed a bug in OS X OpenGL drivers from 10.10.5. I have already fixed this and confirmed the fix with users who still run 10.10.5, so this bug fix will ship in 11.32 for sure. In the meantime, turn off HDR to work around the problem.

Also, if you are a Mac user running 10.10.5, consider updating to a newer Mac OS!

Weather Crash

The most mysterious crash we see is new to 11.31 – a mysterious crash in the weather code. This crash is mysterious to us because nothing changed anywhere near this code from 11.30 to 11.31. The crash reports also don’t make a ton of sense – Sidney and I spent a few hours last night staring at disassembly and being baffled.

I have been contacting users who auto-reported this crash, and fortunately the response to running some test builds for this has been quite positive. I’m hoping to narrow down the change that caused this so that we can wrap our heads around what went wrong.

This weather crash is the one I am most concerned about because it is both unrelated to anything we changed and introduced in 11.31 – a tiny release designed to stabilize, not destabilize the sim. I don’t have a work-around at the time because I don’t have anything like causal steps to reproduce.

Please do not contact me with “I have a crash, can I help” – if we haven’t seen your crash report, there’s no way for you to know if the crash you have is this one or something else. If your email address is in your auto-reports, we can ping you.

Running Out of Mapped GPU Memory

The largest source of instability we’ve seen recently comes from 11.30, and it’s the GPU not being able to provide X-Plane with mapped memory. Since we radically changed the rendering engine in 11.30 (as part of our port toward Vulkan) I am not surprised to see a major GPU problem, but it is still a top priority to fix it. This bug is equally common in 11.30 and 11.31, appears to affect AMD and NVidia windows users (but perhaps AMD more – we’re not sure), but isn’t something we see on our lab machines.  Sidney and I have some ideas on how to at least work around the problem so that people can fly.

Performance Problems

We’ve heard a lot of chatter about performance problems and complaints about performance loss, and we are collecting detailed performance reports from users so we can see what’s going on. Since the performance tests are automated, it’s relatively quick for us to gather this data.

So far, while we have seen a lot of mediocre performance (and mediocre hardware!), we have not yet measured via tests the kind of “catastrophic” performance problems that one might expect from the amount of complaining on forums, etc. That doesn’t mean there isn’t a serious problem out there, it just means we haven’t seen it.

For performance, my view is: if we find something truly awful (e.g. the sim used to run at 25 fps and now runs at 5 fps after the update), we’ll go fix it. I don’t want to make anyone’s copy of X-Plane impossible to use.

But if someone is seeing a 5-10% loss of performance, at this point it’s better to ignore it, because the same engineers who would analyze and fix the performance problems (Sidney and myself) are the ones who are doing the Vulkan port, and the Vulkan port gives us a better shot at fixing performance than trying to beat more performance out of the OpenGL driver stack. In fact, even analyzing the problem is more possible with Vulkan, because the OpenGL drivers do a number of expensive things that they give us no visibility into.

To give you an example of what I mean: we captured performance data from a user with an older Ryzen 16-core CPU and a GeForce 1080 GTX. Our analysis showed: 20-30 fps in the highest fps test (basically everything maxed out), 50-60 fps in medium settings, and 60-70 fps at the lowest settings. At all times, the GeForce 1080 was not maxed out and the CPU was the bottleneck.

Here’s the thing: the older Ryzen CPU has a single-core Geekbench score about as good as my 2014 iMac – that is, it’s not a top tier CPU, it’s old, and it was never optimized for single threaded performance. The user’s system is unbalanced for X-Plane (a lot more GPU than needed for that CPU), and 20-30 fps with everything maxed out is all I would expect from a CPU of that performance level.

So there’s no sign that the machine is underperforming our expectations. And the obvious thing to do to make the system faster is to be more multi-core (since the machine has 16 cores). And that means: focus on Vulkan.

So when it comes to performance, I’m going to beg patience and try to not lose momentum on the Vulkan/Metal port. In the long term it’s a better way to help everyone go faster. If we find something truly bad though, we will go and investigate more.

I don’t know what the ETA is for 11.32, but my plan is days, not weeks. The crash bugs are our top priority right now.

About Ben Supnik

Ben is a software engineer who works on X-Plane; he spends most of his days drinking coffee and swearing at the computer -- sometimes at the same time.

44 comments on “11.31 and Bug Squashing

  1. Anything about the autopilot and other avionics problems reported by some users? Anything we should be aware of for now?

  2. Nice post and update. Sounds like my machine in the example. 16 core Threadripper and GTX1080. Sim performs well with medium settings. I have never maxed out the system settings. I also realized an RTX–2080ti is way to much for this mis-match between CPU and GPU. Looking forward to a multi core future with the Vulcan! Loved the post!

    1. Yeah – the 1080 is excessive unless you’re going to push the monitor res (e.g. for HDR + 4k, my 1070 is the bottlenecked, but for 4K + LDR, even my 1070 is fine), so the 2080 is overkill.

      1. But a good GPU is essential for decent frame rates in VR. Saying that, even in VR it’s my CPU which is the bottleneck, and I’m running a i7-8700K @5.1Ghz (with a 1080ti). When I built this machine (specifically for X-Plane) I was looking for the fastest single thread bench CPU, but I couldn’t afford it 🙂 Vulkan is my hope, it should do a lot for so many of us even those running slower multi-core cpus.
        Thanks for the informative update Ben.

        1. I think that depends on your HMD res and definition of decent. IF you are going to do VR at 45 fps (half rate) on a first-gen headset like the Rift, the 10070 is fine. If you want to run at 90 fps (and do whatever it takes to your CPU to get there) and run on a larger display headset and/or crank up the super sampling, you’re going to need more.

          I bring up the CPU-GPU thing because we see the combo of “overpowered GPU relative to CPU” a _lot_ more than vice versa…that is, of the people who complain to us about FPS, it’s quite common that they’ve updated the GPU on an older CPU, and gotten no net improvement. (That’s often why they are complaining. 🙂

  3. @Ben

    I believe I am experiencing this “Driver” bug which you described above for the Mac OS 10, but on Windows with an older Nvidia 780 Ti driver (I commented on your prior posting here and also sent in a bug report).

    Will the bug fix you are going to publish with 11.32 also cover Nvidia on Windows?

      1. Thanks. Just now somebody confirmed to have encountered the issue on Linux as well.
        See //
        therein the message of user “wolsoft” with a log.txt attached.

        I have got a 2nd XP copy here setup for beta / rc testing. As soon as something gets available for Windows I will have a look.
        If you need earlier checks, feel free to sent email with details (my email address should be part of my bug report or this posting).

  4. What do you recommend for people looking towards upgrading to a ryzen system with integrated graphics (laptop), given that most ryzen cpus are designed for multi-threaded performance boosts?

    1. Yes…stay away, far away from anything with an integrated GPU! A good processor, doesn’t matter if it’s a top of the line AMD or Intel, will be severely hamstrung by a weak GPU.

      Better to get a laptop built around a dedicated GPU such as Nvidia 1050ti or better.

  5. I have a question: If the S-TEC ALT mode causes “trim jitter” (adjusts trim by less than 0.05 notches with a frequency higher than 0.5 Hz), is that a bug? I noticed it in the Cessna while keeping a stable level flight at 2000ft.

  6. Hi,
    First thanks for the hard work you all are putting into the sim.

    I just want to update (and I’ll file a bug right after this), that I think I found a bug related to the XPSDK probing. When I use lat/long and probe for elevation I receive wrong heights (on v11.31r1) but when I use information from camera location I receive the correct height.

    To be sure, I had the luck to have a backup of v11.26 where I tested the probing of the exact same location, but this time I received the expected height in both ways.

    I sample 4 coordinates elevation in a tight vicinity,
    In v11.26 I receive for elevation probe:
    lat: 47.269946, lon: 11.331731, elev_ft: 2452.39

    In v11.31r1 I receive:
    lat: 47.269946, lon: 11.331731, elev_ft: 329.456

    Again, I publish these findings here too, in the hope it will help to confirm others suspicion too, or maybe receive confirmation from other community member to strengthen my claim.


  7. Hi Ben,
    I did spot a memory problem in 11.30, would load up my 16gb ram then get out of memory (would not swap out to virtual ram)
    11.31 the most I have seen is 14gb then drops to about 9gb when the program starts.
    Tweaking the video setting obviously changes the amount of video ram being used.
    Anyway 11.30 and 11.31 has given me the best performance to date, not perfect but it NEVER will be.
    Don’t know how you guys keep up this pace in the development team, please don’t have burnout

    Just for info systems spec
    Intel i7
    16gb Ram
    1080Ti 11gb
    M.2 drives
    Thanks for a superb SIM

    1. Talking about program start: When starting the spash screen appears, then the screen goes dark for a very long time while the sim is loading. I’d prefer seeing at least some progess meter (if no spash screen is possible). It’s for quite a long time like that, and I was hoping it will be automagically fixed “some day”…

      The other thing is when a new flight displays for the first time, everything is frozen for a few seconds (1-3s). I’m curious: Why is that so, and is there anything to be done against that? I can suspect that all the threads doing various updates start at once, and the CPU or GPU is massively overloaded. If that’s the case, can’d the threads be started by priority, or (even better (while poor in Windows) given a priority relative to the importance of the task)?

  8. Generally the FPS is not a factor except with heavy clouds rendering, I am running a 1080 GTX and i7-7700K. However with one exception, the particle effects. As an example, let’s say you boot up on the runway. Then activate the “engine fire” and switch to outside view. Now you can watch the performance decreases heavily while the smoke and flames encapsulate the plane. I think many of the recent “Dude, I have a huuuuuuge FPS drop” reports are mainly now due to the new particle system. I also would imagine that this will be more manageable with Vulcan/Metal.

    So good luck to both of you…

    1. I wonder whether it would help against massive drop of frame rate if automatically updating clouds or smoke less frequently if frame rate drops. Black smoke with outside view makes my framerate drop below 5fps, while (with a non-high-end card) I’m having about 30fps…
      Since a very long time rendering clouds (and other semi-transparant staructures) is the biggest performance hit.

  9. Glad you guys are working on the “Out of memory issue” using a gtx 1060 6gb, 16gb RAM and a i7-6700 non k, i was running all high on 11.30 beta and it was fine but once i updated to release 11.30 i keep getting the *X-plane has ran out of memory* error but im glad you guys and girls are working on it 🙂

  10. I ve got problem with fps but only when I’m high above clouds, above ex. fl240. Then fps decrease from 35-45 to under 19. This problem has been started from 11.30…now in 11.31 is worst.

    1. I’ve noticed something similar to this.

      Before 11.30, cruise was the smother flight, with higher fps. Now, is on ground when those fps are higher (and with objects setting on max, higher than 11.26 settings), and cruise go over 30 fps (in my case). Not a bug for me, just as a comment.

  11. Hello.
    it is not possible to put somewhere in xplane our email adress for reporting bug. i think on a mac a ctd (crash to desktop) is reporting to apple with a report bug.
    I don’t know if after apple transmit bug to Laminar research.

    1. For the Mac this is true – the auto-crash reporter for OS X stopped working when Apple changed the low level OS APIs that the library we use (Breakpad) uses to catch the crashes, and we have not yet restored this. For OSX, if you auto-report, it goes to Apple, not us. You can attach the report manually to a bug report.

  12. your doing a great job wit X-plane.

    By the way is it possible to do something for the water planes in the near future too. Anchor : when the anchor is set in x-plane every plane makes dancing circles and jumps.

  13. Ben you mention that Mac users running 10.10.5 should consider updating to a newer Mac OS. Does X-Plane 11.31 support Apple’s latest OS Mojave? At the end of last year there was a lot of people stating don’t update at that time due to issues arising post installation

    1. Most of the dev team is running Mojave these days. Certainly if you run into issues, we’d like to hear about it in the bug reporter. (There are currently zero bugs in our bug database that match either “Mojave” or “10.14”… so if there are issues, we’re not aware of them! 😀 )

  14. Please if you can get a look at the still popping up lights in the distance…

    Amazing work xplane!!!

  15. On a “normal” PC that runs the Witcher 3 (on max) with 60 fps
    XP 11 runs with 7 – 10 fps (on max)!

    Just my personal comparison.
    Ryzen 5 2600 / 16GB / RX580

    1. That has already been answered many times.

      1. XP is not made to put _every_ graphics slider on max, especially not without total high-end Hardware.

      2. Comparing XP to such a game, is like buying a 28 tons truck and saying “my Ferrari does 325 km/h, this truck only 80”, or complaining about your Ferrari beeing extremely unpractical for a move.
      In that game, can you fly a 747 from NY City to Dubai?

  16. I have reported a strange observation when beginning a flight.
    My fps goes haywire at first, presumably while stuff is loaded in though pre 11.3 it didn’t happen, and then settles but after that if I just sit on the runway and touch nothing my fps gradually reduces frame by frame so that I can go from 45fps to 35 fps in a few minutes just sitting there without any input whatsoever.
    I have 32GB RAM , 1080Ti, i5 6600K running at 4.3Ghz on SSD and windows 10.
    This “bug” has only started with 11.3 and I mention it because it may behind some of the performance issues people are reporting – that performance degrades as though there is a memory leak or something.

    Great work though guys, rooting for you and Vulkan!

    1. I have same experience. Just loading the flight, sitting on tarmac fps goes down gradually from lets say 45 to 38fps in about 30sec. It is repeatable and doesn’t depends on locality, time or weather.

      1. I wonder: Could that be some automatic power saving, or the GPU throttling automatically due to heat? An other explanation could be clouds moving across. Maybe we need a “freeze weather” (i.e.: don’t change) mode to debug that 😉

  17. X-plane will suddenly have a fps huge drop when loading new .dsf files.Please fix it.Thank you.

  18. 11.31 Windows 10, i5-6600 CPU @ 3.30GHz, 4 cores, 32Gb ram, GeForce GTX 960 4Gb. With everything maxed except for reflections @ min, I get a very respectable 24 to 40 fps depending on the # of guages displayed on the Skyhawk Float dash and density of vfr sceenery. but was just double checking and had a strange skid left after kissing the ground so watched it in replay and crashed to desk top, 1st CTDT in for ever. An auto report was sent. Thank you things in general are much smoother.
    There are 2 things I hope to see fixed the floats still dipping below the water occasionally and the coasting physics on water after engine cut off, it goes on forever!

  19. Think I found the culprit of my problem below: The smoke rendering is eating my frames. Smoke from buildings, ships and other objects cause drops after your last patches. Please fix. A lot of smoke “objects” are in this scenery below.

    Posted in your blog: January 15, 2019 at 5:18 am

    Thanks devs and a Happy New Year @ll.

    Still waiting here for improvements and sadly your 11.3x has killed my airport in frames. With 11.2x it was tolerable. Start on Runway 08.

    My scenery: //

    My sys: i5 4670k @ 4.7 & 1080ti

  20. I love how transparent you are about all this. It inspires a lot of confidence and makes people more patient. Thanks for the update!

  21. Your transparency on the issue is a lesson to be learned by other major of the software industry. Nevertheless my sim is now closed until patches as we have no way to revert back to 11.30… could be an option to allow people to dare trying sub version but being able to revert quickly .. the two copy option is to heavy to manage in terms of versioning of the plugins, addon and sceneries … the goal is to flight no ? Not being release managers. Thanks for the dedication to the support of Xplane ( beside the current situation you changed my sim life that à started with fs9 )

  22. Is it not possible to downgrade to 11.30? My x-plane is unable to function more than 5 minutes in a row.

  23. Intel® Core (TM) i7-9700k CPU @ 3.60 Ghz (4.9Ghz Turbo)
    32GB RAM
    SEAHAWK 1080TI 11GB
    Rocking out in 4k with nice frames, a little low and slow at start, however after a min or so it’s pushing 30 to 40 fps with shadows, and sliders maxed out.

  24. Actually I messup the maths: When writing 0.5 Hz, I actually meant 2 Hz (what makes matters worse)…

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