Unhandled Exception: FormatException: Unexpected extension byte (at offset 21)

I'm getting an error decoding the buffer, my zip file is encoded in ANSI. How fix?

final inputStream = InputFileStream(item.path!);
final archive = ZipDecoder().decodeBuffer(inputStream);

E/flutter (27669): [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: FormatException: Unexpected extension byte (at offset 21)
E/flutter (27669): #0      _Utf8Decoder.convertSingle (dart:convert-patch/convert_patch.dart:1789:7)
E/flutter (27669): #1      Utf8Decoder.convert (dart:convert/utf.dart:351:42)
E/flutter (27669): #2      InputFileStream.readString
package:archive/…/io/input_file_stream.dart:355
E/flutter (27669): #3      new ZipFileHeader
package:archive/…/zip/zip_file_header.dart:45
E/flutter (27669): #4      new ZipDirectory.read
package:archive/…/zip/zip_directory.dart:53
E/flutter (27669): #5      ZipDecoder.decodeBuffer

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! Doctor found issues in 1 category.

kineapps / flutter_archive

Unhandled Exception: FormatException: Unexpected extension byte (at offset 21) #56