diff --git a/lib-src/libflac/src/libFLAC/stream_encoder.c b/lib-src/libflac/src/libFLAC/stream_encoder.c
index 45bdb252b..cc6b16166 100644
--- a/lib-src/libflac/src/libFLAC/stream_encoder.c
+++ b/lib-src/libflac/src/libFLAC/stream_encoder.c
@@ -1469,7 +1469,8 @@ FLAC_API FLAC__bool FLAC__stream_encoder_finish(FLAC__StreamEncoder *encoder)
 
 	if(0 != encoder->private_->file) {
 		if(encoder->private_->file != stdout)
-			fclose(encoder->private_->file);
+			error = fflush(encoder->private_->file) ||
+				fclose(encoder->private_->file);
 		encoder->private_->file = 0;
 	}
 
diff --git a/src/FFmpeg.cpp b/src/FFmpeg.cpp
index eecb44587..380070004 100644
--- a/src/FFmpeg.cpp
+++ b/src/FFmpeg.cpp
@@ -209,10 +209,17 @@ int ufile_close(AVIOContext *pb)
 {
    std::unique_ptr<wxFile> f{ (wxFile *)pb->opaque };
 
-   if (f)
-      f->Close();
+   bool success = true;
+   if (f) {
+      success = f->Flush() && f->Close();
+      pb->opaque = nullptr;
+   }
 
-   return 0;
+   // We're not certain that a close error is for want of space, but we'll
+   // guess that
+   return success ? 0 : -ENOSPC;
+
+   // Implicitly destroy the wxFile object here
 }
 
 // Open a file with a (possibly) Unicode filename
diff --git a/src/FFmpeg.h b/src/FFmpeg.h
index ebdcfd0b3..c3807382f 100644
--- a/src/FFmpeg.h
+++ b/src/FFmpeg.h
@@ -928,6 +928,18 @@ private:
 
 // Deleter adaptor for functions like av_free that take a pointer
 template<typename T, typename R, R(*Fn)(T*)> struct AV_Deleter {
+   inline R operator() (T* p) const
+   {
+      R result{};
+      if (p)
+         result = Fn(p);
+      return result;
+   }
+};
+
+// Specialization of previous for void return
+template<typename T, void(*Fn)(T*)>
+struct AV_Deleter<T, void, Fn> {
    inline void operator() (T* p) const
    {
       if (p)
@@ -959,9 +971,19 @@ using AVCodecContextHolder = std::unique_ptr<
 using AVDictionaryCleanup = std::unique_ptr<
    AVDictionary*, AV_Deleter<AVDictionary*, void, av_dict_free>
 >;
-using UFileHolder = std::unique_ptr<
+struct UFileHolder : public std::unique_ptr<
    AVIOContext, AV_Deleter<AVIOContext, int, ufile_close>
->;
+>
+{
+   // Close explicitly, not ignoring return values.
+   int close()
+   {
+      auto result = get_deleter() ( get() );
+      release();
+      return result;
+   }
+};
+
 template<typename T> using AVMallocHolder = std::unique_ptr<
    T, AV_Deleter<void, void, av_free>
 >;
diff --git a/src/FileFormats.cpp b/src/FileFormats.cpp
index e1fc3c59a..badfb5fd1 100644
--- a/src/FileFormats.cpp
+++ b/src/FileFormats.cpp
@@ -288,7 +288,7 @@ OSType sf_header_mactype(int format)
 
 ODLock libSndFileMutex;
 
-void SFFileCloser::operator() (SNDFILE *sf) const
+int SFFileCloser::operator() (SNDFILE *sf) const
 {
    auto err = SFCall<int>(sf_close, sf);
    if (err) {
@@ -299,4 +299,5 @@ void SFFileCloser::operator() (SNDFILE *sf) const
          (_("Error (file may not have been written): %s"),
          buffer));
    }
+   return err;
 }
diff --git a/src/FileFormats.h b/src/FileFormats.h
index e2361f688..08dc57b37 100644
--- a/src/FileFormats.h
+++ b/src/FileFormats.h
@@ -127,7 +127,16 @@ inline R SFCall(F fun, Args&&... args)
 }
 
 //RAII for SNDFILE*
-struct SFFileCloser { void operator () (SNDFILE*) const; };
-using SFFile = std::unique_ptr<SNDFILE, SFFileCloser>;
+struct SFFileCloser { int operator () (SNDFILE*) const; };
+struct SFFile : public std::unique_ptr<SNDFILE, SFFileCloser>
+{
+   // Close explicitly, not ignoring return values.
+   int close()
+   {
+      auto result = get_deleter() ( get() );
+      release();
+      return result;
+   }
+};
 
 #endif
diff --git a/src/FileIO.cpp b/src/FileIO.cpp
index bc59040df..ecaca8b54 100644
--- a/src/FileIO.cpp
+++ b/src/FileIO.cpp
@@ -52,11 +52,18 @@ bool FileIO::IsOpened()
    return mOpen;
 }
 
-void FileIO::Close()
+bool FileIO::Close()
 {
-   mOutputStream.reset();
+   bool success = true;
+   if (mOutputStream) {
+      // mOutputStream->Sync() returns void!  Rrr!
+      success = mOutputStream->GetFile()->Flush() &&
+         mOutputStream->Close();
+      mOutputStream.reset();
+   }
    mInputStream.reset();
    mOpen = false;
+   return success;
 }
 
 wxInputStream & FileIO::Read(void *buf, size_t size)
diff --git a/src/FileIO.h b/src/FileIO.h
index 5200503df..404638aa3 100644
--- a/src/FileIO.h
+++ b/src/FileIO.h
@@ -32,7 +32,7 @@ class FileIO
 
    bool IsOpened();
 
-   void Close();
+   bool Close();
 
    wxInputStream & Read(void *buffer, size_t size);
    wxOutputStream & Write(const void *buffer, size_t size);
@@ -41,7 +41,7 @@ class FileIO
    wxString mName;
    FileIOMode mMode;
    std::unique_ptr<wxInputStream> mInputStream;
-   std::unique_ptr<wxOutputStream> mOutputStream;
+   std::unique_ptr<wxFFileOutputStream> mOutputStream;
    bool mOpen;
 };
 
diff --git a/src/export/ExportFFmpeg.cpp b/src/export/ExportFFmpeg.cpp
index a01a11b20..118d082fb 100644
--- a/src/export/ExportFFmpeg.cpp
+++ b/src/export/ExportFFmpeg.cpp
@@ -945,6 +945,12 @@ ProgressResult ExportFFmpeg::Export(AudacityProject *project,
       if ( !Finalize() ) // Finalize makes its own messages
          return ProgressResult::Cancelled;
 
+   if ( mUfileCloser.close() != 0 ) {
+      // TODO: more precise message
+      AudacityMessageBox(_("Unable to export"));
+      return ProgressResult::Cancelled;
+   }
+
    return updateResult;
 }
 
diff --git a/src/export/ExportFLAC.cpp b/src/export/ExportFLAC.cpp
index 0c4647a3e..efc2d38dc 100644
--- a/src/export/ExportFLAC.cpp
+++ b/src/export/ExportFLAC.cpp
@@ -335,10 +335,13 @@ ProgressResult ExportFLAC::Export(AudacityProject *project,
    mMetadata.reset();
 
    auto cleanup2 = finally( [&] {
+      if (!(updateResult == ProgressResult::Success ||
+            updateResult == ProgressResult::Stopped)) {
 #ifndef LEGACY_FLAC
-      f.Detach(); // libflac closes the file
+         f.Detach(); // libflac closes the file
 #endif
-      encoder.finish();
+         encoder.finish();
+      }
    } );
 
    const WaveTrackConstArray waveTracks =
@@ -389,6 +392,20 @@ ProgressResult ExportFLAC::Export(AudacityProject *project,
       }
    }
 
+   if (updateResult == ProgressResult::Success ||
+       updateResult == ProgressResult::Stopped) {
+#ifndef LEGACY_FLAC
+      f.Detach(); // libflac closes the file
+#endif
+      if (!encoder.finish())
+         // Do not reassign updateResult, see cleanup2
+         return ProgressResult::Failed;
+#ifdef LEGACY_FLAC
+      if (!f.Flush() || !f.Close())
+         return ProgressResult::Failed;
+#endif
+   }
+
    return updateResult;
 }
 
diff --git a/src/export/ExportMP2.cpp b/src/export/ExportMP2.cpp
index 4fd603ea5..0b790962b 100644
--- a/src/export/ExportMP2.cpp
+++ b/src/export/ExportMP2.cpp
@@ -330,7 +330,11 @@ ProgressResult ExportMP2::Export(AudacityProject *project,
          return ProgressResult::Cancelled;
       }
 
-   outFile.Close();
+   if ( !outFile.Close() ) {
+      // TODO: more precise message
+      AudacityMessageBox(_("Unable to export"));
+      return ProgressResult::Cancelled;
+   }
 
    return updateResult;
 }
diff --git a/src/export/ExportMP3.cpp b/src/export/ExportMP3.cpp
index 8c0b2a60f..667db2de7 100644
--- a/src/export/ExportMP3.cpp
+++ b/src/export/ExportMP3.cpp
@@ -854,7 +854,7 @@ public:
    int FinishStream(unsigned char outbuffer[]);
    void CancelEncoding();
 
-   void PutInfoTag(wxFFile & f, wxFileOffset off);
+   bool PutInfoTag(wxFFile & f, wxFileOffset off);
 
 private:
 
@@ -1393,17 +1393,21 @@ void MP3Exporter::CancelEncoding()
    mEncoding = false;
 }
 
-void MP3Exporter::PutInfoTag(wxFFile & f, wxFileOffset off)
+bool MP3Exporter::PutInfoTag(wxFFile & f, wxFileOffset off)
 {
    if (mGF) {
       if (mInfoTagLen > 0) {
          // FIXME: TRAP_ERR Seek and writ ein MP3 exporter could fail.
-         f.Seek(off, wxFromStart);
-         f.Write(mInfoTagBuf, mInfoTagLen);
+         if ( !f.Seek(off, wxFromStart))
+            return false;
+         if (mInfoTagLen > f.Write(mInfoTagBuf, mInfoTagLen))
+            return false;
       }
 #if defined(__WXMSW__)
       else if (beWriteInfoTag) {
-         f.Flush();
+         if ( !f.Flush() )
+            return false;
+         // PRL:  What is the correct error check on the return value?
          beWriteInfoTag(mGF, OSOUTPUT(f.GetName()));
          mGF = NULL;
       }
@@ -1413,7 +1417,10 @@ void MP3Exporter::PutInfoTag(wxFFile & f, wxFileOffset off)
       }
    }
 
-   f.SeekEnd();
+   if ( !f.SeekEnd() )
+      return false;
+
+   return true;
 }
 
 #if defined(__WXMSW__)
@@ -1801,7 +1808,7 @@ ProgressResult ExportMP3::Export(AudacityProject *project,
    bool endOfFile;
    id3len = AddTags(project, id3buffer, &endOfFile, metadata);
    if (id3len && !endOfFile) {
-      if (id3len < outFile.Write(id3buffer.get(), id3len)) {
+      if (id3len > outFile.Write(id3buffer.get(), id3len)) {
          // TODO: more precise message
          AudacityMessageBox(_("Unable to export"));
          return ProgressResult::Cancelled;
@@ -1887,7 +1894,7 @@ ProgressResult ExportMP3::Export(AudacityProject *project,
             break;
          }
 
-         if (bytes < outFile.Write(buffer.get(), bytes)) {
+         if (bytes > outFile.Write(buffer.get(), bytes)) {
             // TODO: more precise message
             AudacityMessageBox(_("Unable to export"));
             updateResult = ProgressResult::Cancelled;
@@ -1909,7 +1916,7 @@ ProgressResult ExportMP3::Export(AudacityProject *project,
       }
 
       if (bytes > 0) {
-         if (bytes < outFile.Write(buffer.get(), bytes)) {
+         if (bytes > outFile.Write(buffer.get(), bytes)) {
             // TODO: more precise message
             AudacityMessageBox(_("Unable to export"));
             return ProgressResult::Cancelled;
@@ -1918,7 +1925,7 @@ ProgressResult ExportMP3::Export(AudacityProject *project,
 
       // Write ID3 tag if it was supposed to be at the end of the file
       if (id3len > 0 && endOfFile) {
-         if (bytes < outFile.Write(id3buffer.get(), id3len)) {
+         if (bytes > outFile.Write(id3buffer.get(), id3len)) {
             // TODO: more precise message
             AudacityMessageBox(_("Unable to export"));
             return ProgressResult::Cancelled;
@@ -1931,9 +1938,9 @@ ProgressResult ExportMP3::Export(AudacityProject *project,
       //
       // Also, if beWriteInfoTag() is used, mGF will no longer be valid after
       // this call, so do not use it.
-      exporter.PutInfoTag(outFile, pos);
-
-      if (!outFile.Close()) {
+      if (!exporter.PutInfoTag(outFile, pos) ||
+          !outFile.Flush() ||
+          !outFile.Close()) {
          // TODO: more precise message
          AudacityMessageBox(_("Unable to export"));
          return ProgressResult::Cancelled;
diff --git a/src/export/ExportOGG.cpp b/src/export/ExportOGG.cpp
index 0a71fb2e5..51b420cb7 100644
--- a/src/export/ExportOGG.cpp
+++ b/src/export/ExportOGG.cpp
@@ -359,7 +359,11 @@ ProgressResult ExportOGG::Export(AudacityProject *project,
       }
    }
 
-   outFile.Close();
+   if ( !outFile.Close() ) {
+      updateResult = ProgressResult::Cancelled;
+      // TODO: more precise message
+      AudacityMessageBox(_("Unable to export"));
+   }
 
    return updateResult;
 }
diff --git a/src/export/ExportPCM.cpp b/src/export/ExportPCM.cpp
index 50641950a..44c819181 100644
--- a/src/export/ExportPCM.cpp
+++ b/src/export/ExportPCM.cpp
@@ -530,7 +530,7 @@ ProgressResult ExportPCM::Export(AudacityProject *project,
       
       // Install the WAV metata in a "LIST" chunk at the end of the file
       if (updateResult == ProgressResult::Success ||
-          updateResult == ProgressResult::Stopped)
+          updateResult == ProgressResult::Stopped) {
          if ((sf_format & SF_FORMAT_TYPEMASK) == SF_FORMAT_WAV ||
              (sf_format & SF_FORMAT_TYPEMASK) == SF_FORMAT_WAVEX) {
             if (!AddStrings(project, sf.get(), metadata, sf_format)) {
@@ -538,6 +538,12 @@ ProgressResult ExportPCM::Export(AudacityProject *project,
                AudacityMessageBox(_("Unable to export"));
                return ProgressResult::Cancelled;
             }
+         }
+         if (0 != sf.close()) {
+            // TODO: more precise message
+            AudacityMessageBox(_("Unable to export"));
+            return ProgressResult::Cancelled;
+         }
       }
    }
 
@@ -545,6 +551,7 @@ ProgressResult ExportPCM::Export(AudacityProject *project,
        updateResult == ProgressResult::Stopped)
       if (((sf_format & SF_FORMAT_TYPEMASK) == SF_FORMAT_AIFF) ||
           ((sf_format & SF_FORMAT_TYPEMASK) == SF_FORMAT_WAV))
+         // Note: file has closed, and gets reopened and closed again here:
          if (!AddID3Chunk(fName, metadata, sf_format) ) {
             // TODO: more precise message
             AudacityMessageBox(_("Unable to export"));
@@ -845,6 +852,9 @@ bool ExportPCM::AddID3Chunk(wxString fName, const Tags *tags, int sf_format)
       if (4 != f.Write(&sz, 4))
          return false;
 
+      if (!f.Flush())
+         return false;
+
       if (!f.Close())
          return false;
    }