I found a resolution that is reliable. I feel had to go to the extremes to copy the shared cache symbols from my watch. For my Apple Watch symbol-copy problem, I had to use both the UI setting and a caffeinate session while Xcode is preparing the watch. I had to keep the MacBook plugged in and do this: Apple menu → System Settings → Battery → Options Turn on: Prevent automatic sleeping on power adapter when the display is off Apple describes this setting as preventing the Mac from sleeping while plugged in even if the display is off. Then go to: System Settings → Lock Screen Set: Turn display off on power adapter when inactive: Never Apple’s Lock Screen settings control when the display turns off while on power adapter. Then, I had to go to the terminal command for extra insurance, and run this: caffeinate -dimsu Leave that Terminal window open while Xcode is preparing the watch. Meaning: -d prevent display sleep -i prevent idle sleep -m prevent disk sleep -s prevent system sleep while plugged in -u declare user activity When you are done, press: Control + C For good measure, I used my wife's automatic clicker that she uses for her phone, so that I could click on my apple watch, to keep it awake. The device looks like this: https://www.walmart.com/ip/Automatic-Clicker-for-Phone-Auto-Screen-Clicker-Screen-Device-Automatic-Tapp/17945065201?wmlspartner=wlpa&selectedSellerId=103146102&sourceid=dsn_gdn_0c92c416-dbd6-42ec-845c-ecf69af2153d&veh=dsn&wmlspartner=dsn_gdn_0c92c416-dbd6-42ec-845c-ecf69af2153d&cn=0042_fy27_mp_mpa_lo_int_dis_pmax-p13n&wl9=pla&wl11=online&gad_source=1&gad_campaignid=23148469844&gbraid=0AAAAADmfBIpy4X5QmYJAMTTnDovmz6_yD&gclid=EAIaIQobChMIkJPwzISClQMVGCdECB0wdhppEAQYBCABEgJCqfD_BwE Crazy work. I feel I shouldn't have had to go through all of this, but I guess it is what it is for the time being. I hope all. of this helps those run encounter trouble with this in the future.

Thanks for your replies. I appreciate you... I received a news flash the other day. In my case, I have security software installed on my Mac that monitors and filters all network traffic. When Xcode tries to find iPhones or iPads on the same local network, it uses special local-network discovery traffic. That security software blocks or intercepts that traffic because it looks like unknown or unmanaged network activity. As a result, Xcode can’t see devices that are actually there. The devices weren’t the problem — the security software was. I had to temporarily stop it so Xcode could communicate directly with my local network. Crazy work man. So for those in a professional environment, temporarily close the security software and allow XCode to run its course. This worked for me.

Thanks for your reply... Here is the information you have requested: Request xcrun devicectl list preferredDDI Response Host CoreDevice version: 397.21 The DDI used for the iOS platform: • hostDDI: file:///Library/Developer/DeveloperDiskImages/iOS_DDI.dmg ▿ ddiMetadata: • buildUpdate: 16A242d • contentIsCompatible: true • coreDeviceVersionChecksIncludeDevelopmentRevision: true • developmentRevision: 0 • enforcingCoreDeviceVersionChecks: true • platform: iOS ▿ projectMetadata: • Citrine-94 • CoreDevice-397.21 • DTDeveloperDiskImageSupport-14.0.0 • DTOCMock-23002 • GPUToolsDevice_DDI-300.21 • JetsamProperties-2205 • LiveExecutionResultsLogger-20002 • Mercury-54 • XCTest-23196 • isUsable: true • variant: external The DDI used for the tvOS platform: • hostDDI: file:///Library/Developer/DeveloperDiskImages/tvOS_DDI.dmg ▿ ddiMetadata: • buildUpdate: 16A242d • contentIsCompatible: true • coreDeviceVersionChecksIncludeDevelopmentRevision: true • developmentRevision: 0 • enforcingCoreDeviceVersionChecks: true • platform: tvOS ▿ projectMetadata: • Citrine-94 • CoreDevice-397.21 • DTDeveloperDiskImageSupport-14.0.0 • DTOCMock-23002 • GPUToolsDevice_DDI-300.21 • JetsamProperties-2205 • LiveExecutionResultsLogger-20002 • Mercury-54 • XCTest-23196 • isUsable: true • variant: external The DDI used for the watchOS platform: • hostDDI: file:///Library/Developer/DeveloperDiskImages/watchOS_DDI.dmg ▿ ddiMetadata: • buildUpdate: 16A242d • contentIsCompatible: true • coreDeviceVersionChecksIncludeDevelopmentRevision: true • developmentRevision: 0 • enforcingCoreDeviceVersionChecks: true • platform: watchOS ▿ projectMetadata: • Citrine-94 • CoreDevice-397.21 • DTDeveloperDiskImageSupport-14.0.0 • DTOCMock-23002 • GPUToolsDevice_DDI-300.21 • JetsamProperties-2205 • LiveExecutionResultsLogger-20002 • Mercury-54 • XCTest-23196 • isUsable: true • variant: external The DDI used for the visionOS platform: • hostDDI: file:///Library/Developer/DeveloperDiskImages/xrOS_DDI.dmg ▿ ddiMetadata: • buildUpdate: 16A242d • contentIsCompatible: true • coreDeviceVersionChecksIncludeDevelopmentRevision: true • developmentRevision: 0 • enforcingCoreDeviceVersionChecks: true • platform: xrOS ▿ projectMetadata: • Citrine-94 • CoreDevice-397.21 • DTDeveloperDiskImageSupport-14.0.0 • DTOCMock-23002 • GPUToolsDevice_DDI-300.21 • JetsamProperties-2205 • LiveExecutionResultsLogger-20002 • Mercury-54 • XCTest-23196 • isUsable: true • variant: external Other Request xcrun devicectl device info ddiServices --device <My UDID> Other Response 10:18:53 Acquired tunnel connection to device. 10:18:53 Enabling developer disk image services. ERROR: The developer disk image could not be staged on the host. (com.apple.dt.CoreDeviceError error 12045 (0x2F0D)) NSURL = file:///Library/Developer/DeveloperDiskImages/iOS_DDI.dmg DeviceIdentifier = FC91CD07-395E-4AD4-826B-FECB15FCB740 -------------------------------------------------------------------------------- ERROR: Couldn’t communicate with a helper application. (NSCocoaErrorDomain error 4099 (0x1003)) NSDebugDescription = The connection to service created from an endpoint was invalidated: failed at lookup with error 9 - Bad file descriptor. As far as the sudo chmod 0777 /private/var/tmp, the root user owns that folder. I've also added additional information to the ticket I submitted. Thanks for all that you are doing for me. I'm humbled and am grateful.

Here is the FB number: FB15289146 Thank you!

We resolved my problem. I updated the XCode project(s) in question. The iOS target was changed from 12.0 to 14.0 The only question that remains in my world would explaining why I encountered the problems I was seeing, because I don't understand it.