Found this thread after doing a Google search. Just spent my entire day on this exact same issue: Same error message ("Data couldn't be read...") Same CI setup (Jenkins) Same Xcode (Xcode 26 Beta 4) You hit the nail on the head with the comment about how there's some sort of issue with actool + ibtool. For us, the actool that ships with Beta 4 is busted in both Jenkins builds and also in Terminal. Xcode 26 Beta 4 In Beta 4, actool --version returns as if it's ibtool (note the "com.apple.ibtool.version" in the output): % /Applications/Xcode-26.0.0-Beta.4.app/Contents/Developer/usr/bin/actool --version <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>com.apple.ibtool.version</key> <dict> <key>bundle-version</key> <string>24112</string> <key>short-bundle-version</key> <string>26.0</string> </dict> </dict> </plist> Xcode 26 Beta 3 But in Beta 3, it's normal ("com.apple.actool.version"): % /Applications/Xcode-26.0.0-Beta.3.app/Contents/Developer/usr/bin/actool --version <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>com.apple.actool.version</key> <dict> <key>bundle-version</key> <string>24093.9</string> <key>short-bundle-version</key> <string>26.0</string> </dict> </dict> </plist> Conclusion In the end, we concluded that there's something just fundamentally busted about actool in Beta 4. Dropped back to Beta 3 and everything works. Really hoping to run "actool --version" in the upcoming Beta 5 and see it work correctly. :-)