TranslationMemoryImporter.Import was failed due to Sdl.LanguagePlatform.Core.LanguagePlatformException: 'Sdl.Core.LanguageProcessing.ICU2.WordBoundaryFinder on 2019SR2CU6

TranslationMemoryImporter.Import was failed due to Sdl.LanguagePlatform.Core.LanguagePlatformException: 'Sdl.Core.LanguageProcessing.ICU2.WordBoundaryFinder on 2019SR2CU6. My code worked fine before i upgrades TradosSR2.

FileBasedTranslationMemory tm = new FileBasedTranslationMemory(tmpSDLTM);
TranslationMemoryImporter importer = new TranslationMemoryImporter(tm.LanguageDirection);

foreach (ProjectFile pf in projectFiles)
{
importer.Import(pf.LocalFilePath);
}

Here is exception log.

Sdl.LanguagePlatform.Core.LanguagePlatformException: 'Sdl.Core.LanguageProcessing.ICU2.WordBoundaryFinder' のタイプ初期 化子が例外をスローしました。
場所 Sdl.LanguagePlatform.TranslationMemoryApi.FileBasedTranslationMemoryLanguageDirection.AddTranslationUnitsMasked(TranslationUnit[] translationUnits, ImportSettings settings, Boolean[] mask)
場所 Sdl.LanguagePlatform.TranslationMemoryApi.TranslationMemoryLanguageDirectionImportExport.AddTranslationUnitsMask(TranslationUnit[] tus, ImportSettings settings, Boolean[] mask)
場所 Sdl.Core.TM.ImportExport.Importer.ProcessBufferedTUs(ImportStatistics stats)
場所 Sdl.Core.TM.ImportExport.Importer.Flush(ImportStatistics stats)
場所 Sdl.Core.TM.ImportExport.BilingualContentImporter.FileComplete()
場所 Sdl.FileTypeSupport.Framework.Core.Utilities.BilingualApi.BilingualContentHandlerAdapter.FileComplete()
場所 Sdl.FileTypeSupport.Framework.Integration.AbstractBilingualProcessorContainer.FileComplete()
場所 Sdl.FileTypeSupport.Framework.Integration.MultiFileConverter.FileComplete()
場所 Sdl.FileTypeSupport.Framework.BilingualApi.AbstractBilingualContentProcessor.FileComplete()
場所 Sdl.FileTypeSupport.Framework.Integration.AbstractBilingualProcessorContainer.FileComplete()
場所 Sdl.FileTypeSupport.Bilingual.SdlXliff.XliffFileReader.OnEndFile()
場所 Sdl.FileTypeSupport.Bilingual.SdlXliff.SdlXliffFeeder.<>c.<ContinueScanning>b__14_2(ISdlXliffStreamContentHandler handler)
場所 System.Collections.Generic.List`1.ForEach(Action`1 action)
場所 Sdl.FileTypeSupport.Bilingual.SdlXliff.SdlXliffFeeder.ContinueScanning()
場所 Sdl.FileTypeSupport.Bilingual.SdlXliff.XliffFileReader.ContinueParsing()
場所 Sdl.FileTypeSupport.Bilingual.SdlXliff.XliffFileReader.ParseNext()
場所 Sdl.FileTypeSupport.Framework.Integration.FileExtractor.ParseNext()
場所 Sdl.FileTypeSupport.Framework.Integration.MultiFileConverter.ParseNext()
場所 Sdl.FileTypeSupport.Framework.Integration.MultiFileConverter.Parse()
場所 Sdl.Core.TM.ImportExport.Importer.ImportBilingualFile(String fileName)
場所 Sdl.Core.TM.ImportExport.Importer.Import(String fileName, IImportDestination importDestination)
場所 Sdl.LanguagePlatform.TranslationMemoryApi.TranslationMemoryImporter.Import(String fileName)

After i changed target platform from 4.7 to 4.7.2. Exception was disappeared and i could generated sdltm correctly.

As far as i know, .Net4.7 is required .net framework for 2019 plugin development. Is there any requirement change to build plugin for 2019SR2?

Should i change target platform to 4.7.2?

Best regards,

Masayuki