When using Guzzle Client in artisan tinker, macOS throws objc[86150]: +[__NSCFConstantString initialize] may have been in progress in another thread when fork() was called. This is caused by the Objective-C runtime’s safety check during fork.

Disable the Fork Safety Check

Set an environment variable to skip the check:

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export OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES

Add it to ~/.bashrc or ~/.zshrc so you don’t have to set it manually every time.

References

• GuzzleHttp GitHub Repository — Guzzle HTTP client source code and issue tracker
• Laravel Artisan Tinker Documentation — artisan tinker REPL usage guide
• macOS fork() Safety: OBJC_DISABLE_INITIALIZE_FORK_SAFETY — Background on Objective-C runtime and fork safety