diff --git a/searchlib/src/vespa/searchlib/diskindex/pagedict4file.cpp b/searchlib/src/vespa/searchlib/diskindex/pagedict4file.cpp
index a5f49c2a3fe3..96649d27b82b 100644
--- a/searchlib/src/vespa/searchlib/diskindex/pagedict4file.cpp
+++ b/searchlib/src/vespa/searchlib/diskindex/pagedict4file.cpp
@@ -403,6 +403,7 @@ PageDict4FileSeqWrite::open(const vespalib::string &name,
 bool
 PageDict4FileSeqWrite::close()
 {
+    bool success = true;
     _pWriter->flush();
     uint64_t usedPBits = _pe.getWriteOffset();
     uint64_t usedSPBits = _spe.getWriteOffset();
@@ -415,28 +416,28 @@ PageDict4FileSeqWrite::close()
     _ssWriteContext.writeComprBuffer(true);
 
     _pWriteContext.dropComprBuf();
-    _pfile.Sync();
-    _pfile.Close();
+    success &= _pfile.Sync();
+    success &= _pfile.Close();
     _pWriteContext.setFile(nullptr);
     _spWriteContext.dropComprBuf();
-    _spfile.Sync();
-    _spfile.Close();
+    success &= _spfile.Sync();
+    success &= _spfile.Close();
     _spWriteContext.setFile(nullptr);
     _ssWriteContext.dropComprBuf();
-    _ssfile.Sync();
-    _ssfile.Close();
+    success &= _ssfile.Sync();
+    success &= _ssfile.Close();
     _ssWriteContext.setFile(nullptr);
 
     // Update file headers
-    updatePHeader(usedPBits);
-    updateSPHeader(usedSPBits);
-    updateSSHeader(usedSSBits);
+    success &= updatePHeader(usedPBits);
+    success &= updateSPHeader(usedSPBits);
+    success &= updateSSHeader(usedSSBits);
 
     _pWriter.reset();
     _spWriter.reset();
     _ssWriter.reset();
 
-    return true;
+    return success;
 }
 
 
@@ -548,7 +549,7 @@ PageDict4FileSeqWrite::makeSSHeader(const FileHeaderContext &fileHeaderContext)
 }
 
 
-void
+bool
 PageDict4FileSeqWrite::updatePHeader(uint64_t fileBitSize)
 {
     vespalib::FileHeader h(FileSettings::DIRECTIO_ALIGNMENT);
@@ -560,12 +561,13 @@ PageDict4FileSeqWrite::updatePHeader(uint64_t fileBitSize)
     h.putTag(Tag("frozen", 1));
     h.putTag(Tag("fileBitSize", fileBitSize));
     h.rewriteFile(f);
-    f.Sync();
-    f.Close();
+    bool success = f.Sync();
+    success &= f.Close();
+    return success;
 }
 
 
-void
+bool
 PageDict4FileSeqWrite::updateSPHeader(uint64_t fileBitSize)
 {
     vespalib::FileHeader h(FileSettings::DIRECTIO_ALIGNMENT);
@@ -577,12 +579,13 @@ PageDict4FileSeqWrite::updateSPHeader(uint64_t fileBitSize)
     h.putTag(Tag("frozen", 1));
     h.putTag(Tag("fileBitSize", fileBitSize));
     h.rewriteFile(f);
-    f.Sync();
-    f.Close();
+    bool success = f.Sync();
+    success &= f.Close();
+    return success;
 }
 
 
-void
+bool
 PageDict4FileSeqWrite::updateSSHeader(uint64_t fileBitSize)
 {
     vespalib::FileHeader h(FileSettings::DIRECTIO_ALIGNMENT);
@@ -597,8 +600,9 @@ PageDict4FileSeqWrite::updateSSHeader(uint64_t fileBitSize)
     assert(wordNum <= _sse._numWordIds);
     h.putTag(Tag("numWordIds", wordNum));
     h.rewriteFile(f);
-    f.Sync();
-    f.Close();
+    bool success = f.Sync();
+    success &= f.Close();
+    return success;
 }
 
 
diff --git a/searchlib/src/vespa/searchlib/diskindex/pagedict4file.h b/searchlib/src/vespa/searchlib/diskindex/pagedict4file.h
index 0a68be7ae1bf..8d2340c0b391 100644
--- a/searchlib/src/vespa/searchlib/diskindex/pagedict4file.h
+++ b/searchlib/src/vespa/searchlib/diskindex/pagedict4file.h
@@ -108,9 +108,9 @@ class PageDict4FileSeqWrite : public index::DictionaryFileSeqWrite
     void makePHeader(const FileHeaderContext &fileHeaderContext);
     void makeSPHeader(const FileHeaderContext &fileHeaderContext);
     void makeSSHeader(const FileHeaderContext &fileHeaderContext);
-    void updatePHeader(uint64_t fileBitSize);
-    void updateSPHeader(uint64_t fileBitSize);
-    void updateSSHeader(uint64_t fileBitSize);
+    bool updatePHeader(uint64_t fileBitSize);
+    bool updateSPHeader(uint64_t fileBitSize);
+    bool updateSSHeader(uint64_t fileBitSize);
 public:
     PageDict4FileSeqWrite();
     ~PageDict4FileSeqWrite();
diff --git a/searchlib/src/vespa/searchlib/diskindex/zcposting.cpp b/searchlib/src/vespa/searchlib/diskindex/zcposting.cpp
index f4bee9f6344a..4441b868b159 100644
--- a/searchlib/src/vespa/searchlib/diskindex/zcposting.cpp
+++ b/searchlib/src/vespa/searchlib/diskindex/zcposting.cpp
@@ -258,7 +258,7 @@ Zc4PostingSeqWrite::makeHeader(const FileHeaderContext &fileHeaderContext)
 }
 
 
-void
+bool
 Zc4PostingSeqWrite::updateHeader()
 {
     vespalib::FileHeader h;
@@ -271,8 +271,9 @@ Zc4PostingSeqWrite::updateHeader()
     h.putTag(Tag("fileBitSize", _fileBitSize));
     h.putTag(Tag("numWords", _writer.get_num_words()));
     h.rewriteFile(f);
-    f.Sync();
-    f.Close();
+    bool success = f.Sync();
+    success &= f.Close();
+    return success;
 }
 
 
@@ -320,11 +321,11 @@ Zc4PostingSeqWrite::close()
     _writer.on_close(); // flush and pad
     auto &writeContext = _writer.get_write_context();
     writeContext.dropComprBuf();
-    _file.Sync();
-    _file.Close();
+    bool success = _file.Sync();
+    success &= _file.Close();
     writeContext.setFile(nullptr);
-    updateHeader();
-    return true;
+    success &= updateHeader();
+    return success;
 }
 
 void
diff --git a/searchlib/src/vespa/searchlib/diskindex/zcposting.h b/searchlib/src/vespa/searchlib/diskindex/zcposting.h
index 24fccee9b8d2..dc23fe5b37e3 100644
--- a/searchlib/src/vespa/searchlib/diskindex/zcposting.h
+++ b/searchlib/src/vespa/searchlib/diskindex/zcposting.h
@@ -61,6 +61,11 @@ class Zc4PostingSeqWrite : public index::PostingListFileSeqWrite
     FastOS_File      _file;
     uint64_t _fileBitSize;
     index::PostingListCountFileSeqWrite *const _countFile;
+    /**
+     * Make header using feature encode write context.
+     */
+    void makeHeader(const search::common::FileHeaderContext &fileHeaderContext);
+    bool updateHeader();
 public:
     Zc4PostingSeqWrite(index::PostingListCountFileSeqWrite *countFile);
     ~Zc4PostingSeqWrite();
@@ -81,12 +86,6 @@ class Zc4PostingSeqWrite : public index::PostingListFileSeqWrite
     void getParams(PostingListParams &params) override;
     void setFeatureParams(const PostingListParams &params) override;
     void getFeatureParams(PostingListParams &params) override;
-
-    /**
-     * Make header using feature encode write context.
-     */
-    void makeHeader(const search::common::FileHeaderContext &fileHeaderContext);
-    void updateHeader();
 };
 
 class ZcPostingSeqWrite : public Zc4PostingSeqWrite