[kambala]

Digged a bit and found the actual errors:

-[IXSErrorPresenter presentErrorForBundleIDs:code:underlyingError:errorSource:]: Asked to present alert for error 17 source MobileInstallation underlying error Error Domain=MIInstallerErrorDomain Code=13 "Failed to verify code signature of /var/installd/Library/Caches/com.apple.mobile.installd.staging/temp.QGrwCI/extracted/Payload/MyApp.app : 0xe8008029 (The code signature version is no longer supported.)" UserInfo={NSLocalizedDescription=Failed to verify code signature of /var/installd/Library/Caches/com.apple.mobile.installd.staging/temp.QGrwCI/extracted/Payload/MyApp.app : 0xe8008029 (The code signature version is no longer supported.), LegacyErrorString=ApplicationVerificationFailed, FunctionName=+[MICodeSigningVerifier _validateSignatureAndCopyInfoForURL:withOptions:error:], SourceFileLine=74, LibMISErrorNumber=-402620375} for bundle IDs (
    "com.my.app"
)

trustd[852]/1#12 LF=0 copy_parent_certificates Error Domain=NSOSStatusErrorDomain Code=-34018 "Client has neither application-identifier nor keychain-access-groups entitlements" UserInfo={numberOfErrorsDeep=0, NSDescription=Client has neither application-identifier nor keychain-access-groups entitlements}

Looks like the only solution is to install Xcode 13 beta (but I believe just the command line tools would be enough) which requires Big Sur 11.4 (or Monterey beta). Guide: https://www.reddit.com/r/AltStore/commen...on_ios_15/

Edit: Xcode 12.5 should be sufficient, but it requires Big Sur as well.

Just installed 19.0 and it’s working, not sure what’s up with 19.1

what if you try now with 19.1 again? Did you install from Big Sur?