Happy to report that I solved the issue by uninstalling Xcode 12.5 and installing Xcode 11.7. Works without an issue now.

Okay, so I erased my discs and did a fresh OS install (Big Sur) followed by Xcode 12.5. Bam, same issue again. Created a new project from scratch, went straight to storyboard and there it was again, the log is below. At this point, I have pretty much given up any hope of solving this issue without help from Apple. ================================= XCODE VERSION INFO: ================================= Version = 12.5 (12E262) Plugin Version = 18122 Beta Version = 4 OS Version = 11.3.1 (20E241) ================================= ASSERTION: ================================= Failed to update scene 'BYZ-38-t0r' with IBUIViewAutolayoutGuide (x1), UIView (x1), and UIViewController (x1). Exception name: IBPlatformToolFailureException Exception reason: The tool closed the connection Application Specific Information:** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Failed to create remote render context' terminating with uncaught exception of type NSException abort() called CoreSimulator 757.5 - Device: iPhone Xʀ (7AFA8D5E-C28E-48EE-A30D-DC82F30208E2) - Runtime: iOS 14.5 (18E182) - DeviceType: iPhone Xʀ

I checked the entire thread and tried every single solution proposed, none of the worked for me. I will now try a factory reset of my system and see if it makes any difference.

Claude : I did all that and checked again, still same issue. Will file a bug report. OOPer : Yes I am thinking that is most likely the issue since I upgraded Mac OS to Big Sur. How do I go about fixing the Mac environment in case it is broken which it most likely is?

Hi Claude, It is a different project, a new project that I created with no additions, I just created a new project, went straight to storyboard and bam, the issue was there already. Here is the XML part of this project (it is an iOS project) - Simulator version is 12.5 (961.1) ?xml version="1.0" encoding="UTF-8"? document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="18122" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="BYZ-38-t0r"   device id="retina6_1" orientation="portrait" appearance="light"/   dependencies     plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="18093"/     capability name="Safe area layout guides" minToolsVersion="9.0"/     capability name="System colors in document resources" minToolsVersion="11.0"/     capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/   /dependencies   scenes     !--View Controller--     scene sceneID="tne-QT-ifu"       objects         viewController id="BYZ-38-t0r" customClass="ViewController" customModule="SAMPLE_PROJECT" customModuleProvider="target" sceneMemberID="viewController"           view key="view" contentMode="scaleToFill" id="8bC-Xf-vdC"             rect key="frame" x="0.0" y="0.0" width="414" height="896"/             autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/             subviews               label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Label" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="IPf-ol-yH6"                 rect key="frame" x="200" y="52" width="0.0" height="253"/                 autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/                 fontDescription key="fontDescription" type="system" pointSize="17"/                 nil key="textColor"/                 nil key="highlightedColor"/               /label             /subviews             viewLayoutGuide key="safeArea" id="6Tk-OE-BBY"/             color key="backgroundColor" systemColor="systemBackgroundColor"/           /view         /viewController         placeholder placeholderIdentifier="IBFirstResponder" id="dkx-z0-nzr" sceneMemberID="firstResponder"/       /objects       point key="canvasLocation" x="95.652173913043484" y="77.678571428571431"/     /scene   /scenes   resources     systemColor name="systemBackgroundColor"       color white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/     /systemColor   /resources /document

Hi, I downloaded & installed Xcode 12.5 but face the same issue. Even when I create a new project, I get the same error. The following is the log from a new project I created, when I opened the storyboard, same issue - ================================= XCODE VERSION INFO: ================================= Version = 12.5 (12E262) Plugin Version = 18122 Beta Version = 4 OS Version = 11.2.3 (20D91) ================================= ASSERTION: ================================= Failed to update scene 'BYZ-38-t0r' with IBUIViewAutolayoutGuide (x1), UILabel (x1), UIView (x1), and UIViewController (x1). Exception name: IBPlatformToolFailureException Exception reason: The tool closed the connection Application Specific Information: ASSERTION FAILURE in /Library/Caches/com.apple.xbs/Sources/IBSimulatorComponents/IDEInterfaceBuilderCocoaTouch-18093/SimulatorComponents/IBCocoaTouchTool/IBCocoaTouchTool.m:354 Details: Expecting an object package for incremental session 0DC7D599-A117-4256-BF0B-4BFF7B68B7A0, active sessions = (null), context = (null), last closed session = (null) Object: IBCLICocoaTouchTool: 0x7fe5c1f0a1c0