If I change the optimization level of the release build to 'None [-O0]' then everything works again. It also works if I set the optimization level to [-Ofast].

This bug is still there as of Xcode 12.5.1... Fix still applies. Would be nice to get this patched into the release builds of Xcode since the default disk name is "Macintosh HD" and the space in that breaks the included build-scripts.

Update: 24 hours and a handful of attempts later, I finally have 12.5.1 successfully installed. Here's hoping something changes by the time 12.5.2 rolls around.

Clearly I'm not the only one experiencing this as most of the recent reviews are about simply downloading/installing Xcode.

I have an alternate solution for others having a similar error here: https://developer.apple.com/forums/thread/665287

Found the issue and have a fix. Go to: /Applications/Xcode.app/Contents/SharedFrameworks/ContentDeliveryServices.framework/Versions/A/itms/bin You'll find: iTMSTransporter This is simply a build script so open it up in your favorite text editor (I like TextMate). Change this line: JVM_LIB_PATH="-Djava.library.path=${ESCAPED_WOA_TOP_LEVEL}/macOS/lib:${HOME}/Library/Java/Extensions:/Library/Java/Extensions:/Network/Library/Java/Extensions:/System/Library/Java/Extensions:/usr/lib/java:." To this: JVM_LIB_PATH="-Djava.library.path=\"${ESCAPED_WOA_TOP_LEVEL}\"/macOS/lib:\"${HOME}\"/Library/Java/Extensions:/Library/Java/Extensions:/Network/Library/Java/Extensions:/System/Library/Java/Extensions:/usr/lib/java:." Basically just add a few backslash-escaped quotes around ${ESCAPED_WOA_TOP_LEVEL} and ${HOME}. Enjoy successful Xcode uploads again!! :)

5 months later and I still can't upload apps through Xcode... Transporter is still working as a backup method for now. Archive in Xcode - Distribute - Export Then add the IPA to Transporter. Tried using altool in terminal and it fails as well. I need to be able to send app updates through Xcode, but I guess since Apple won't help out here I'll be diving into this more myself this week. Will report back when I find something.