I just started receiving the dreaded C++ Assertion Error whenever I try to start a flight. See this thread here for what I am dealing with:
This is marked as solved, but it is most definitely NOT solved. I tried every fix in that thread, and nothing works. Has anyone else figured out how to solve this error? In that thread people have tried reinstalling the game to no avail. Do I have to reinstall Windows, or is there an actual fix for this?
Thanks for any help.
Hi @wushuguy1,
No fix is needed.
This error is because you have Visual Studio installed with debugging on. The error that is throwing to the debugger is ātrappedā in MSFS and thrown out. In order to stop VS from trapping it first is to turn off debugging in VS.
I believe youāre wrong with this. This shows up because the DLL in question is triggering an assert in a piece of code compiled in debug mode. This assertion has nothing to do at all with any development program installed on the end user computer, and even the fact the popup window is showing has nothing to do with it.
It is therefore not fixed because this assertion means there is a bug nonetheless in the DLLā¦ And from the look of it, this might be a bug in a function parsing a file and expecting a certain āformatā.
I ended up just reformatting my computer and reinstalling MSFS. Everything works fine now. I know these may have been drastic measures, but I was having other issues with constant crashes in VR mode. That seems to have resolved as well. Hopefully things will keep running as smooth as they are now.
I had this problem as well & I used Process Explorer and compared FS 2020 working on a separate Windows install on the same machine vs nonworking FS 2020 on my main Windows 10 partition. Turns out DLLs from FastPictureViewer were loaded by the FlightSimulator.exe process. Once I uninstalled FastPictureViewer, FS 2020 started working.
Just updated to the 1.13.16.0, But Assertion failed when loading the fly. Tried to delete some files like some topicsās saying, but found my folders are different.
Ouchā¦ Either stack####_ are pointers to bytes, or they should remove the sizeof(T) in there, or donāt use signed arithmetic if stackTop_ is higher than stackEnd_ 
MODERATOR EDIT: This post merged from another topic:
Iāve tried to reinstall the whole sim and reinstall, but it still didnāt work
Iām on the Microsoft Store version.
Iām installed the sim in a custom disk, not using the default one is on"D drive"
Also see this Archived topic:
https://forums.flightsimulator.com/t/visual-c-error-message-assertion-error/304953
Iām still having an issue of unable to control the plane, no throttle and control at all
Hi, please use another category for that. Do a search in this category:
Latest Bugs & Issues/Aircraft Systems topics - Microsoft Flight Simulator Forums
Thank you.
MODERATOR EDIT: The following 2 posts were merged into this topic.
There is also archive topic here:
https://forums.flightsimulator.com/t/solved-microsoft-visual-c-runtime-library-assertion-failed/279475
Hi Guys, can anyone explain to me the mistake that came out of me?
i meet the same issue,how to fix it?
Hi @HuggableKitty88! Welcome to the forum!
Try disabling any development program you may have that has any real-time debugging turned on.
This shows up because this DLL, MicrosoftGeospatialTiles.dll is a core module in the game which wasnāt compiled in release mode but debug mode. This assertion means there is a bug nonetheless in the DLLā¦ And from the look of it, this might be a bug in a function parsing a file and expecting a certain āformatā.
Moreover, this assertion has nothing to do at all with any development program installed on the end user computer, and even the fact the popup window is showing has nothing to do with it.
In short: these is nothing you can do but wait Microsoft releases release mode DLLs instead of debug mode DLLs.
[edited: removed bold text]
I have deleted the āRolling Cacheā. Under General Options>Data.
This worked for me.
Thank you so much for this! I just reinstalled MSFS after a long hiatus and found your post. I would have never figured this out.
As @CptLucky8 says ā¦
ASSERT expression are not evaluated in the Release version of a program, so somehow a debug version got distributed.
The question now is ā Either Intentionally, or unintentionally ?? 
