I am getting the following error which was NOT present on Xcode 11. I have trouble reproducing the issue since this is a large project and I can't pinpoint the file in which it happens. The error doesn't say which file it is.
1 swift 0x0000000107e1b865 llvm::sys::RunSignalHandlers() + 85
2 swift 0x0000000107e1ce1f SignalHandler(int) + 111
3 libsystemplatform.dylib 0x00007fff73ac35fd sigtramp + 29
4 libsystemplatform.dylib 0x00007ffe00000002 sigtramp + 18446744067473918498
5 swift 0x0000000107df11bc llvm::vfs::VFSFromYamlDirIterImpl::incrementImpl(bool) + 156
6 swift 0x0000000107df10fd llvm::vfs::VFSFromYamlDirIterImpl::VFSFromYamlDirIterImpl(llvm::Twine const&, std::1::wrapiter<std::1::uniqueptr<llvm::vfs::RedirectingFileSystem::Entry, std::1::defaultdelete<llvm::vfs::RedirectingFileSystem::Entry> >>, std::1::wrapiter<std::1::uniqueptr<llvm::vfs::RedirectingFileSystem::Entry, std::1::defaultdelete<llvm::vfs::RedirectingFileSystem::Entry> >>, bool, llvm::vfs::FileSystem&, std::1::errorcode&) + 141
7 swift 0x0000000107dee3d8 llvm::vfs::RedirectingFileSystem::dirbegin(llvm::Twine const&, std::1::errorcode&) + 216
8 swift 0x0000000107a5c628 clang::HeaderSearch::loadSubdirectoryModuleMaps(clang::DirectoryLookup&) + 264
9 swift 0x0000000107a5c264 clang::HeaderSearch::lookupModule(llvm::StringRef, llvm::StringRef, bool) + 916
10 swift 0x0000000107a5be39 clang::HeaderSearch::lookupModule(llvm::StringRef, bool, bool) + 105
11 swift 0x0000000104958b77 swift::ClangImporter::Implementation::loadModuleClang(swift::SourceLoc, llvm::ArrayRef<swift::Located<swift::Identifier> >) + 103
12 swift 0x000000010495969b swift::ClangImporter::loadModule(swift::SourceLoc, llvm::ArrayRef<swift::Located<swift::Identifier> >) + 75
13 swift 0x00000001043fb766 swift::ModuleFile::getModule(llvm::ArrayRef<swift::Identifier>, bool) + 534
14 swift 0x000000010444bdeb swift::ModuleFile::associateWithFileContext(swift::FileUnit*, swift::SourceLoc, bool) + 1787
15 swift 0x00000001044b455d swift::SerializedModuleLoaderBase::loadAST(swift::ModuleDecl&, llvm::Optional<swift::SourceLoc>, llvm::StringRef, std::1::uniqueptr<llvm::MemoryBuffer, std::1::defaultdelete<llvm::MemoryBuffer> >, std::1::uniqueptr<llvm::MemoryBuffer, std::1::defaultdelete<llvm::MemoryBuffer> >, std::1::uniqueptr<llvm::MemoryBuffer, std::1::defaultdelete<llvm::MemoryBuffer> >, bool, bool) + 1037
16 swift 0x00000001044b6a59 swift::SerializedModuleLoaderBase::loadModule(swift::SourceLoc, llvm::ArrayRef<swift::Located<swift::Identifier> >) + 825
17 swift 0x0000000104acb2b6 swift::ASTContext::getStdlibModule(bool) + 406
18 swift 0x0000000103abe869 swift::CompilerInstance::performSemaUpTo(swift::SourceFile::ASTStage_t) + 3497
19 swift 0x000000010398032d swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 6845
20 swift 0x0000000103904c37 main + 1255
21 libdyld.dylib 0x00007fff738cacc9 start + 1
22 libdyld.dylib 0x0000000000000084 start + 18446603338577564604
error: Segmentation fault: 11
Apple Swift version 5.3 (swiftlang-1200.0.29.2 clang-1200.0.30.1)
While reading from 'Swift'
1 swift 0x0000000107e1b865 llvm::sys::RunSignalHandlers() + 85
2 swift 0x0000000107e1ce1f SignalHandler(int) + 111
3 libsystemplatform.dylib 0x00007fff73ac35fd sigtramp + 29
4 libsystemplatform.dylib 0x00007ffe00000002 sigtramp + 18446744067473918498
5 swift 0x0000000107df11bc llvm::vfs::VFSFromYamlDirIterImpl::incrementImpl(bool) + 156
6 swift 0x0000000107df10fd llvm::vfs::VFSFromYamlDirIterImpl::VFSFromYamlDirIterImpl(llvm::Twine const&, std::1::wrapiter<std::1::uniqueptr<llvm::vfs::RedirectingFileSystem::Entry, std::1::defaultdelete<llvm::vfs::RedirectingFileSystem::Entry> >>, std::1::wrapiter<std::1::uniqueptr<llvm::vfs::RedirectingFileSystem::Entry, std::1::defaultdelete<llvm::vfs::RedirectingFileSystem::Entry> >>, bool, llvm::vfs::FileSystem&, std::1::errorcode&) + 141
7 swift 0x0000000107dee3d8 llvm::vfs::RedirectingFileSystem::dirbegin(llvm::Twine const&, std::1::errorcode&) + 216
8 swift 0x0000000107a5c628 clang::HeaderSearch::loadSubdirectoryModuleMaps(clang::DirectoryLookup&) + 264
9 swift 0x0000000107a5c264 clang::HeaderSearch::lookupModule(llvm::StringRef, llvm::StringRef, bool) + 916
10 swift 0x0000000107a5be39 clang::HeaderSearch::lookupModule(llvm::StringRef, bool, bool) + 105
11 swift 0x0000000104958b77 swift::ClangImporter::Implementation::loadModuleClang(swift::SourceLoc, llvm::ArrayRef<swift::Located<swift::Identifier> >) + 103
12 swift 0x000000010495969b swift::ClangImporter::loadModule(swift::SourceLoc, llvm::ArrayRef<swift::Located<swift::Identifier> >) + 75
13 swift 0x00000001043fb766 swift::ModuleFile::getModule(llvm::ArrayRef<swift::Identifier>, bool) + 534
14 swift 0x000000010444bdeb swift::ModuleFile::associateWithFileContext(swift::FileUnit*, swift::SourceLoc, bool) + 1787
15 swift 0x00000001044b455d swift::SerializedModuleLoaderBase::loadAST(swift::ModuleDecl&, llvm::Optional<swift::SourceLoc>, llvm::StringRef, std::1::uniqueptr<llvm::MemoryBuffer, std::1::defaultdelete<llvm::MemoryBuffer> >, std::1::uniqueptr<llvm::MemoryBuffer, std::1::defaultdelete<llvm::MemoryBuffer> >, std::1::uniqueptr<llvm::MemoryBuffer, std::1::defaultdelete<llvm::MemoryBuffer> >, bool, bool) + 1037
16 swift 0x00000001044b6a59 swift::SerializedModuleLoaderBase::loadModule(swift::SourceLoc, llvm::ArrayRef<swift::Located<swift::Identifier> >) + 825
17 swift 0x0000000104acb2b6 swift::ASTContext::getStdlibModule(bool) + 406
18 swift 0x0000000103abe869 swift::CompilerInstance::performSemaUpTo(swift::SourceFile::ASTStage_t) + 3497
19 swift 0x000000010398032d swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 6845
20 swift 0x0000000103904c37 main + 1255
21 libdyld.dylib 0x00007fff738cacc9 start + 1
22 libdyld.dylib 0x0000000000000084 start + 18446603338577564604
error: Segmentation fault: 11