Xcode 10.3 not starting on macOS Big Sur

Since I've upgraded to Big Sur Xcode 10.3 which I need is crashed when I try to launch it. I reinstalled to no avail...

Process: Xcode [943]
Path: /Users/USER/Downloads/Xcode.app/Contents/MacOS/Xcode
Identifier: com.apple.dt.Xcode
Version: 10.3 (14492.2)
Build Info: IDEFrameworks-14492002000000000~2 (10G8)
Code Type: X86-64 (Native)
Parent Process: ??? [1]
Responsible: Xcode [943]
User ID: 501

PlugIn Path: /Users/USER/Downloads/Xcode.app/Contents/Developer/usr/lib/libMainThreadChecker.dylib
PlugIn Identifier: libMainThreadChecker.dylib
PlugIn Version: ??? (64492.1)

Date/Time: 2020-11-19 13:23:03.155 +0100
OS Version: macOS 11.0.1 (20B29)
Report Version: 12
Bridge OS Version: 5.0.1 (18P2561)
Anonymous UUID: 3A5EAA65-D39F-FA97-D7F6-A9504FA39AEC


Time Awake Since Boot: 1100 seconds

System Integrity Protection: enabled

Crashed Thread: 0 Dispatch queue: com.apple.main-thread

Exception Type: EXCBADACCESS (SIGBUS)
Exception Codes: KERNPROTECTIONFAILURE at 0x00007fff237a29b9
Exception Note: EXCCORPSENOTIFY

Termination Signal: Bus error: 10
Termination Reason: Namespace SIGNAL, Code 0xa
Terminating Process: exc handler [943]

VM Regions Near 0x7fff237a29b9:
_TEXT 7fff22c09000-7fff23600000 [ 10.0M] r-x/r-x SM=COW /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit
  • ->

TEXT 7fff23600000-7fff23800000 [ 2048K] r-x/rwx SM=PRV /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit Submap 7fff23800000-7fff40000000 [456.0M] r--/rwx SM=PRV process-only VM submap

Application Specific Information:
/Users/tmiskiew/Downloads/Xcode.app/Contents/Developer/usr/lib/libMainThreadChecker.dylib
ProductBuildVersion: 10G8

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 libMainThreadChecker.dylib 0x000000011ad0c069 swizzleImplementationFast + 115
1 libMainThreadChecker.dylib 0x000000011ad0bef0 addSwizzler + 165
2 libMainThreadChecker.dylib 0x000000011ad0baec
libraryinitializer + 2937
3 dyld 0x000000010e5bfdf5 ImageLoaderMachO::doImageInit(ImageLoader::LinkContext const&) + 321
4 dyld 0x000000010e5c046d ImageLoaderMachO::doInitialization(ImageLoader::LinkContext const&) + 29
5 dyld 0x000000010e5bad1a ImageLoader::recursiveInitialization(ImageLoader::LinkContext const&, unsigned int, char const*, ImageLoader::InitializerTimingList&, ImageLoader::UninitedUpwards&) + 492
6 dyld 0x000000010e5b8b82 ImageLoader::processInitializers(ImageLoader::LinkContext const&, unsigned int, ImageLoader::InitializerTimingList&, ImageLoader::UninitedUpwards&) + 188
7 dyld 0x000000010e5b8c22 ImageLoader::runInitializers(ImageLoader::LinkContext const&, ImageLoader::InitializerTimingList&) + 82
8 dyld 0x000000010e5a96a2 dyld::runInitializers(ImageLoader*) + 82
9 dyld 0x000000010e5b4569 dlopeninternal + 609
10 libdyld.dylib 0x00007fff20354fd0 dlopen
internal(char const*, int, void*) + 177
11 libdyld.dylib 0x00007fff2034387e dlopen + 28
12 com.apple.dt.IDEFoundation 0x0000000104617487 IDEInitializeMainThreadChecker + 400
13 com.apple.dt.IDEFoundation 0x0000000104617e99 IDEInitialize + 1038
14 com.apple.dt.IDEKit 0x000000010526e3cd -[IDEApplicationController applicationWillFinishLaunching:] + 622
...

External Modification Summary:
Calls made by other processes targeting this process:
task
forpid: 0
thread
create: 0
threadsetstate: 0
Calls made by this process:
taskforpid: 0
threadcreate: 0
thread
setstate: 0
Calls made by all processes on this machine:
task
forpid: 543
thread
create: 0
threadsetstate: 0

VM Region Summary:
ReadOnly portion of Libraries: Total=1.0G resident=0K(0%) swappedoutorunallocated=1.0G(100%)
Writable regions: Total=872.0M written=0K(0%) resident=0K(0%) swapped
out=0K(0%) unallocated=872.0M(100%)
Code Block
VIRTUAL REGION
REGION TYPE SIZE COUNT (non-coalesced)
=========== ======= =======
Activity Tracing 256K 1
Dispatch continuations 128.0M 1
Foundation 16K 1
Kernel Alloc Once 8K 1
MALLOC 131.2M 32
MALLOC guard page 24K 4
MALLOCMEDIUM (reserved) 600.0M 5 reserved VM address space (unallocated)
STACK GUARD 56.0M 4
Stack 9752K 4
VM
ALLOCATE 916K 12
_CTF 759 1
DATA 35.0M 567
DATACONST 27.4M 340
_DATADIRTY 1829K 217
_FONTDATA 4K 1
_LINKEDIT 526.6M 77
OBJCRO 61.0M 1
_OBJCRW 2468K 2
_TEXT 530.4M 554
UNICODE 588K 1
mapped file 46.9M 10
shared memory 40K 4
=========== ======= =======
TOTAL 2.1G 1840
TOTAL, minus reserved VM space 1.5G 1840

Model: iMac20,2, BootROM 1554.50.3.0.0 (iBridge: 18.16.12561.0.0,0), 8 processors, 8-Core Intel Core i7, 3,8 GHz, 40 GB, SMC
Graphics: kHW
AMDRadeonPro5700Item, AMD Radeon Pro 5700, spdisplayspciedevice, 8 GB
Memory Module: Slot 1 (Channel A / DIMM 1), 4 GB, DDR4, 2667 MHz, SK Hynix, HMA851S6DJR6N-VK
Memory Module: Slot 2 (Channel A / DIMM 0), 4 GB, DDR4, 2667 MHz, SK Hynix, HMA851S6DJR6N-VK
Memory Module: Slot 3 (Channel B / DIMM 1), 16 GB, DDR4, 2667 MHz, 0000, unknown
Memory Module: Slot 4 (Channel B / DIMM 0), 16 GB, DDR4, 2667 MHz, 0000, unknown
AirPort: spairportwirelesscardtypeairport_extreme (0x14E4, 0x7BF), wl0: Sep 11 2020 17:01:15 version 9.30.440.2.32.5.61 FWID 01-1d69e4b4
Bluetooth: Version 8.0.1f5, 3 services, 27 devices, 1 incoming serial ports
Network Service: Wi-Fi, AirPort, en1
USB Device: USB 3.1 Bus
USB Device: Apple T2 Bus
USB Device: Headset
USB Device: Ambient Light Sensor
USB Device: FaceTime HD Camera (Built-in)
USB Device: Apple T2 Controller
Thunderbolt Bus: iMac, Apple Inc., 58.2

Answered by dentamuhajir in 649167022
I have the same issue. I fixed it by deleting the library Xcode.app/Contents/Developer/usr/lib/libMainThreadChecker.dylib. then the Xcode works again.
After upgrading to macOS Big Sur I installed Xcode 10.1, 10.2.1 and 10.3 on two separate Macs and I can say Xcode 10.x doesn't run on Big Sure. It's crashing each and every time I try to launch it.

Any idea what can be done?

Any idea what can be done?

Get another Mac with an older macOS which can run Xcode 10.2 (or 1 or 3).
Or prepare a storage device which can be used as a startup disk, and install the old macOS into it.

Get another Mac with an older macOS which can run Xcode 10.2 (or 1 or 3).

Yes, I have that and it works. But my question was about how to get Xcode 10.x working on Big Sur.


But my question was about how to get Xcode 10.x working on Big Sur.

I know that, but my answer was no way, you should better find other ways around.
I sent this as a bug report to Apple. I couldn't find any official announcement that would end Xcode 10.x support for Big Sur.
Accepted Answer
I have the same issue. I fixed it by deleting the library Xcode.app/Contents/Developer/usr/lib/libMainThreadChecker.dylib. then the Xcode works again.
14
Xcode 10 is not officially supported on Big Sur. Apple is not going to fix Xcode 10 bugs now that Xcode 12 is out.

Install an older version of macOS on a virtual machine and install Xcode 10.3 on that virtual machine if you need to use Xcode 10.3.
Reportet a bug to Apple. The provided a "courtesy feedback" that Xcode 10.x is not supported on Big Sur. To bad they don't tell people before they upgrade to Big Sur...

Super xcode10.1 is certainly old, but it is one of the necessary tools to redesign old versions of Xcode project and be able to migrate them...

Xcode 10.3 not starting on macOS Big Sur
 
 
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