Xcode is crashing on startup. Any workarounds?

Hi,

When I open an existing project (following https://developer.apple.com/tutorials/swiftui/creating-and-combining-views) in Xcode, it crashes immediately with this "(tabController) should not be nil." error:

Code Block
(tabController) should not be nil.
Process: Xcode [11567]
Path: /Applications/Xcode.app/Contents/MacOS/Xcode
Identifier: com.apple.dt.Xcode
Version: 12.3 (17715)
Build Info: IDEFrameworks-17715000000000000~8 (12C33)
App Item ID:
App External ID:
Code Type: ARM-64 (Native)
Parent Process: ??? [1]
Responsible: Xcode [11567]
User ID: 501
Date/Time: 2020-12-19 01:09:44.783 +1100
OS Version: macOS 11.1 (20C69)
Report Version: 12
Anonymous UUID:
Sleep/Wake UUID:
Time Awake Since Boot: 40000 seconds
Time Since Wake: 310 seconds
System Integrity Protection: enabled
Crashed Thread: 0 Dispatch queue: com.apple.main-thread
Exception Type: EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Exception Note: EXC_CORPSE_NOTIFY
Application Specific Information:
ProductBuildVersion: 12C33
ASSERTION FAILURE in /Library/Caches/com.apple.xbs/Sources/IDEFrameworks/IDEFrameworks-17715/IDEKit/Workspace/IDEWorkspaceDocument.m:3270
Details: (tabController) should not be nil.
Object: <IDEWorkspaceDocument: 0x11d5fdb20>
Method: -commitStateToDictionary:
Thread: <NSThread: 0x140628ff0>{number = 1, name = main}
Open FDs: 38/7168
Hints:
Backtrace:
0 -[IDEAssertionHandler handleFailureInMethod:object:fileName:lineNumber:assertionSignature:messageFormat:arguments:] (in IDEKit)
1 _DVTAssertionHandler (in DVTFoundation)
2 _DVTAssertionFailureHandler (in DVTFoundation)
3 -[IDEWorkspaceDocument showWindows] (in IDEKit)
4 -[DVTStateToken _copyStatefulObjectState] (in DVTFoundation)
5 -[DVTStateToken pushStateToRepositoryAndReturnError:] (in DVTFoundation)
6 -[DVTStateRepository _updateStateIfNeeded] (in DVTFoundation)
7 -[DVTStateRepository collectStateFromRegisteredObjects] (in DVTFoundation)
8 -[IDEWorkspaceDocument writeStateData] (in IDEKit)
9 28-[IDEWorkspaceDocument init]_block_invoke (in IDEKit)
10 -[DVTDelayedInvocation runBlock:] (in DVTFoundation)
11 NSFireDelayedPerform (in Foundation)
12 CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION (in CoreFoundation)
13 CFRunLoopDoTimer (in CoreFoundation)
14 CFRunLoopDoTimers (in CoreFoundation)
15 __CFRunLoopRun (in CoreFoundation)
16 CFRunLoopRunSpecific (in CoreFoundation)
17 RunCurrentEventLoopInMode (in HIToolbox)
18 ReceiveNextEventCommon (in HIToolbox)
19 _BlockUntilNextEventMatchingListInModeWithFilter (in HIToolbox)
20 _DPSNextEvent (in AppKit)
21 -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] (in AppKit)
22 -[DVTApplication nextEventMatchingMask:untilDate:inMode:dequeue:] (in DVTKit)
23 -[NSApplication run] (in AppKit)
24 NSApplicationMain (in AppKit)
25 start (in libdyld.dylib)
abort() called
Application Specific Signatures:
((tabController)) != nil


Are there any workarounds?

Thanks @randomize66

I'm getting the same error in one of my projects. 
A workaround for me is to:
Open a different project
File -> Open Recent
Clean build folder
Close Xcode
Delete DerivedData content for the project
Open the project as usual
Clean build folder once again
Go!

I have figured the work around for this back in December already - in it I would open another Xcode project and then with the project window open, I would open the needed project with File -> Open Recent.

Here's a funny thing: today, that OTHER project has stopped opening too. Amazing.

Now I'm using a third, different project, and apparently I'm running out, but statistically, I'll lose access to all of them only by 2023. Amazing.

Thanks this worked for me. I opened another project and xcode did not crash.

UPDATE to my previous post. Reopening another post did allow xcode to open without crashing; however, my current project failed to open and did in fact crash xcode. This worked for me: deleted my project workspace, deleted my podfile.lock and Pods folder. You may also simply rename at the terminal with: > mv yourprojectfile.workspace to yourprojectfile.workspace.bak or any other name. Do the same for the folder.

reinstalled my pods via > pod install.
So the crash was due to my project. Before you go nuts trying to fix xcode, it may be a good idea to test if it an xcode problem or a project problem. So thanks for your tip: by opening another project, it led me to think this issue was my current project.

Xcode is crashing on startup. Any workarounds?
 
 
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