Did you also update ICU? That error message indicates V8 couldn't create a icu::DateTimePatternGenerator instance.
The Github Actions workflow I use to build STPyV8 automatically fetches the V8 repository, perfoms a checkout of the V8 version I specify in my settings, syncs the code with gclient sync and builds it using the following gn args gn_args = { "dcheck_always_on": "false", "is_component_build": "false", "is_debug": "true" if os.environ.get("STPYV8_DEBUG") else "false", "treat_warnings_as_errors": "false", "use_custom_libcxx": "false", "v8_deprecation_warnings": "true", "v8_enable_disassembler": "false", "v8_enable_i18n_support": "true", "v8_enable_pointer_compression": "false", "v8_enable_31bit_smis_on_64bit_arch": "false", "v8_imminent_deprecation_warnings": "true", "v8_monolithic": "true", "v8_use_external_startup_data": "false", } No manual ICU update then. Try building V8 with debug checks enabled, that should give you a better idea of the root cause. I tried but all I got is this error *** stack smashing detected ***: terminated I perfomed an additional test rebuilding setting v8_enable_i18n_support to false and the issue disappeared. Please be aware that I am able to reproduce the reported issue very reliably on Debian 11 but everything works fine if the same code runs on Gentoo Linux, macOS and Windows. Regards, Angelo -- -- v8-dev mailing list v8-dev@googlegroups.com http://groups.google.com/group/v8-dev --- You received this message because you are subscribed to the Google Groups "v8-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to v8-dev+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/v8-dev/7bee58c0-1d4d-4e09-8885-4ae81d05e876n%40googlegroups.com.