My application (using a nested framework for networking) was working correctly on iPadOS 18, but failed to perform a UDP broadcast operation after upgrading the device to iPadOS 26. The low-level console logs consistently show a "Permission denied" error.
Symptoms & Error Message:
When attempting to send a UDP broadcast packet using NWConnection (or a similar low-level socket call within the framework), the connection fails immediately with the following error logged in the console:
nw_socket_service_writes_block_invoke [C2:1] sendmsg(fd 6, 124 bytes) [13: Permission denied]
(Error code 13 corresponds to EACCES).
Verification Steps (What I have checked):
-
Multicast Networking Entitlement is Approved and Applied:
- The necessary entitlement (
com.apple.developer.networking.multicast) was granted by Apple. - The Provisioning Profile used for signing the Host App Target has been regenerated and explicitly includes "Multicast Networking" capability (see attached screenshot).
- I confirmed that Entitlements cannot be added directly to the Framework Target, only the Host App Target, which is the expected behavior.
- The necessary entitlement (
-
Local Network Privacy is Configured:
- The Host App's Info.plist contains the
NSLocalNetworkUsageDescriptionkey with a clear usage string. - Crucially, the Local Network Access alert does not reliably appear when the Broadcast function is first called (despite a full reinstall after OS upgrade). Even when Local Network Access is manually enabled in Settings, the Broadcast still fails with
EACCES.
- The Host App's Info.plist contains the
-
Code Implementation:
- The Broadcast is attempted using
NWConnectionto the host255.255.255.255on a specific port.
- The Broadcast is attempted using
Request:
Since all required entitlements and profiles are correct, and the failure is a low-level EACCES on a newly updated OS version, I suspect this may be a regression bug in the iPadOS 26 security sandbox when validating the Multicast Networking Entitlement against a low-level socket call (like sendmsg).
Has anyone else encountered this specific Permission denied error on iPadOS 26 with a valid Multicast Entitlement, and is there a known workaround aside from switching to mDNS/Bonjour?
NWConnection isn’t really set up to deal with UDP broadcasts. My advice, sadly, is that you use BSD Sockets for this.
BSD Sockets is a much harder API to use correctly. I have lots of hints and tips in Broadcasts and Multicasts, Hints and Tips. The most critical point is that, when working with broadcasts and multicasts, you should target a specific interface. If you try to send a broadcast without specifying the interface, it’s hard to predict which interface it’ll be sent over.
I suspect this may be a regression bug in the iPadOS 26 security sandbox
Well, it’s certainly a regression, but I doubt it’s in the sandbox. Usually the sandbox causes things to fail with EPERM.
You are feel to file a bug about NWConnection, but I’m concerned that it’ll struggle to get traction given the state of broadcast support in Network framework. If you need a fix for this in the short-to-medium term, I recommend that you switch to BSD Sockets.
If you do file a bug, please post your bug number, just for the record.
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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
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