Fix QSharedMemory on macOS with Qt 6.6+#215
Merged
itay-grudev merged 2 commits intoJun 16, 2026
Merged
Conversation
Qt 6.6+ defaults to POSIX Realtime shared memory via QNativeIpcKey on macOS. However, POSIX shared memory (shm_open) requires Qt to be built with -feature-ipc_posix and has strict naming requirements. Many Qt installations (including Homebrew) don't have POSIX IPC enabled, causing the error: QSharedMemory::KeyError "QSharedMemory::attach (shm_open): bad name" Use legacyNativeKey() to force System V shared memory, which works reliably on all macOS configurations regardless of Qt build options. Fixes single instance detection failing on macOS with Qt 6.6+.
itay-grudev
approved these changes
Jun 16, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Qt 6.6+ defaults to POSIX Realtime shared memory via QNativeIpcKey on macOS. However, POSIX shared memory (shm_open) requires Qt to be built with -feature-ipc_posix and has strict naming requirements.
Many Qt installations (including Homebrew) don't have POSIX IPC enabled, causing the error:
QSharedMemory::KeyError "QSharedMemory::attach (shm_open): bad name"
Use legacyNativeKey() to force System V shared memory, which works reliably on all macOS configurations regardless of Qt build options.
Fixes single instance detection failing on macOS with Qt 6.6+.