diff --git a/src/corelib/io/qabstractfileengine.cpp b/src/corelib/io/qabstractfileengine.cpp
index 43ceb21a57d..4ee29daa7a9 100644
--- a/src/corelib/io/qabstractfileengine.cpp
+++ b/src/corelib/io/qabstractfileengine.cpp
@@ -829,10 +829,10 @@ bool QAbstractFileEngine::unmap(uchar *address)
 
     Returns \c true on success; otherwise, \c false is returned.
  */
-bool QAbstractFileEngine::cloneTo(QAbstractFileEngine *target)
+QAbstractFileEngine::TriStateResult QAbstractFileEngine::cloneTo(QAbstractFileEngine *target)
 {
     Q_UNUSED(target);
-    return false;
+    return TriStateResult::NotSupported;
 }
 
 /*!
diff --git a/src/corelib/io/qabstractfileengine_p.h b/src/corelib/io/qabstractfileengine_p.h
index cc35d3c45d5..ca196305765 100644
--- a/src/corelib/io/qabstractfileengine_p.h
+++ b/src/corelib/io/qabstractfileengine_p.h
@@ -83,6 +83,11 @@ public:
         OwnerGroup
     };
 
+    enum class TriStateResult : qint8 {
+        NotSupported = -1,
+        Failed = 0,
+        Success = 1,
+    };
 
     virtual ~QAbstractFileEngine();
 
@@ -119,7 +124,7 @@ public:
     virtual QDateTime fileTime(QFile::FileTime time) const;
     virtual void setFileName(const QString &file);
     virtual int handle() const;
-    virtual bool cloneTo(QAbstractFileEngine *target);
+    virtual TriStateResult cloneTo(QAbstractFileEngine *target);
     bool atEnd() const;
     uchar *map(qint64 offset, qint64 size, QFile::MemoryMapFlags flags);
     bool unmap(uchar *ptr);
diff --git a/src/corelib/io/qfile.cpp b/src/corelib/io/qfile.cpp
index dcb6f5ce4e0..2a1484e1120 100644
--- a/src/corelib/io/qfile.cpp
+++ b/src/corelib/io/qfile.cpp
@@ -834,7 +834,12 @@ QFile::copy(const QString &newName)
                     out.close();
                     close();
                 } else {
-                    if (!d->engine()->cloneTo(out.d_func()->engine())) {
+                    QAbstractFileEngine::TriStateResult r = d->engine()->cloneTo(out.d_func()->engine());
+                    if (r == QAbstractFileEngine::TriStateResult::Failed) {
+                        d->setError(QFile::CopyError, tr("Could not copy to %1: %2")
+                                    .arg(newName, d->engine()->errorString()));
+                        error = true;
+                    } else if (r == QAbstractFileEngine::TriStateResult::NotSupported) {
                         char block[4096];
                         qint64 totalRead = 0;
                         out.setOpenMode(ReadWrite | Unbuffered);
diff --git a/src/corelib/io/qfilesystemengine_p.h b/src/corelib/io/qfilesystemengine_p.h
index f3f63a96af4..773c1d34f87 100644
--- a/src/corelib/io/qfilesystemengine_p.h
+++ b/src/corelib/io/qfilesystemengine_p.h
@@ -60,6 +60,8 @@ Q_CORE_EXPORT bool qt_isCaseSensitive(const QFileSystemEntry &entry, QFileSystem
 class Q_AUTOTEST_EXPORT QFileSystemEngine
 {
 public:
+    using TriStateResult = QAbstractFileEngine::TriStateResult;
+
     static bool isCaseSensitive(const QFileSystemEntry &entry, QFileSystemMetaData &data);
 
     static QFileSystemEntry getLinkTarget(const QFileSystemEntry &link, QFileSystemMetaData &data);
@@ -86,7 +88,7 @@ public:
     static bool fillMetaData(const QFileSystemEntry &entry, QFileSystemMetaData &data,
                              QFileSystemMetaData::MetaDataFlags what);
 #if defined(Q_OS_UNIX)
-    static bool cloneFile(int srcfd, int dstfd, const QFileSystemMetaData &knownData);
+    static TriStateResult cloneFile(int srcfd, int dstfd, const QFileSystemMetaData &knownData);
     static bool fillMetaData(int fd, QFileSystemMetaData &data); // what = PosixStatFlags
     static QByteArray id(int fd);
     static bool setFileTime(int fd, const QDateTime &newDate,
diff --git a/src/corelib/io/qfilesystemengine_unix.cpp b/src/corelib/io/qfilesystemengine_unix.cpp
index b1e41906e64..15a004df13b 100644
--- a/src/corelib/io/qfilesystemengine_unix.cpp
+++ b/src/corelib/io/qfilesystemengine_unix.cpp
@@ -1068,7 +1068,7 @@ bool QFileSystemEngine::fillMetaData(const QFileSystemEntry &entry, QFileSystemM
 }
 
 // static
-bool QFileSystemEngine::cloneFile(int srcfd, int dstfd, const QFileSystemMetaData &knownData)
+auto QFileSystemEngine::cloneFile(int srcfd, int dstfd, const QFileSystemMetaData &knownData) -> TriStateResult
 {
     QT_STATBUF statBuffer;
     if (knownData.hasFlags(QFileSystemMetaData::PosixStatFlags) &&
@@ -1076,12 +1076,14 @@ bool QFileSystemEngine::cloneFile(int srcfd, int dstfd, const QFileSystemMetaDat
         statBuffer.st_mode = S_IFREG;
     } else if (knownData.hasFlags(QFileSystemMetaData::PosixStatFlags) &&
                knownData.isDirectory()) {
-        return false;   // fcopyfile(3) returns success on directories
+        errno = EISDIR;
+        return TriStateResult::Failed;   // fcopyfile(3) returns success on directories
     } else if (QT_FSTAT(srcfd, &statBuffer) == -1) {
-        return false;
+        // errno was set
+        return TriStateResult::Failed;
     } else if (!S_ISREG((statBuffer.st_mode))) {
         // not a regular file, let QFile do the copy
-        return false;
+        return TriStateResult::NotSupported;
     }
 
     [[maybe_unused]] auto destinationIsEmpty = [dstfd]() {
@@ -1093,7 +1095,7 @@ bool QFileSystemEngine::cloneFile(int srcfd, int dstfd, const QFileSystemMetaDat
 #if defined(Q_OS_LINUX)
     // first, try FICLONE (only works on regular files and only on certain fs)
     if (::ioctl(dstfd, FICLONE, srcfd) == 0)
-        return true;
+        return TriStateResult::Success;
 
     // Second, try sendfile (it can send to some special types too).
     // sendfile(2) is limited in the kernel to 2G - 4k
@@ -1102,30 +1104,34 @@ bool QFileSystemEngine::cloneFile(int srcfd, int dstfd, const QFileSystemMetaDat
     ssize_t n = ::sendfile(dstfd, srcfd, nullptr, SendfileSize);
     if (n == -1) {
         // if we got an error here, give up and try at an upper layer
-        return false;
+        return TriStateResult::NotSupported;
     }
 
     while (n) {
         n = ::sendfile(dstfd, srcfd, nullptr, SendfileSize);
         if (n == -1) {
-            // uh oh, this is probably a real error (like ENOSPC), but we have
-            // no way to notify QFile of partial success, so just erase any work
-            // done (hopefully we won't get any errors, because there's nothing
-            // we can do about them)
+            // uh oh, this is probably a real error (like ENOSPC)
             n = ftruncate(dstfd, 0);
             n = lseek(srcfd, 0, SEEK_SET);
             n = lseek(dstfd, 0, SEEK_SET);
-            return false;
+            return TriStateResult::Failed;
         }
     }
 
-    return true;
+    return TriStateResult::Success;
 #elif defined(Q_OS_DARWIN)
     // try fcopyfile
-    return fcopyfile(srcfd, dstfd, nullptr, COPYFILE_DATA | COPYFILE_STAT) == 0;
+    if (fcopyfile(srcfd, dstfd, nullptr, COPYFILE_DATA | COPYFILE_STAT) == 0)
+        return TriStateResult::Success;
+    switch (errno) {
+    case ENOTSUP:
+    case ENOMEM:
+        return TriStateResult::NotSupported;    // let QFile try
+    }
+    return TriStateResult::Failed;
 #else
     Q_UNUSED(dstfd);
-    return false;
+    return TriStateResult::NotSupported;
 #endif
 }
 
diff --git a/src/corelib/io/qfsfileengine_p.h b/src/corelib/io/qfsfileengine_p.h
index c8ed1f71dc8..8744a8f53ef 100644
--- a/src/corelib/io/qfsfileengine_p.h
+++ b/src/corelib/io/qfsfileengine_p.h
@@ -93,7 +93,7 @@ public:
     qint64 read(char *data, qint64 maxlen) override;
     qint64 readLine(char *data, qint64 maxlen) override;
     qint64 write(const char *data, qint64 len) override;
-    bool cloneTo(QAbstractFileEngine *target) override;
+    TriStateResult cloneTo(QAbstractFileEngine *target) override;
 
     virtual bool isUnnamedFile() const
     { return false; }
diff --git a/src/corelib/io/qfsfileengine_unix.cpp b/src/corelib/io/qfsfileengine_unix.cpp
index afcbb104413..45a8332512b 100644
--- a/src/corelib/io/qfsfileengine_unix.cpp
+++ b/src/corelib/io/qfsfileengine_unix.cpp
@@ -648,15 +648,18 @@ bool QFSFileEnginePrivate::unmap(uchar *ptr)
 /*!
     \reimp
 */
-bool QFSFileEngine::cloneTo(QAbstractFileEngine *target)
+QAbstractFileEngine::TriStateResult QFSFileEngine::cloneTo(QAbstractFileEngine *target)
 {
     Q_D(QFSFileEngine);
     if ((target->fileFlags(LocalDiskFlag) & LocalDiskFlag) == 0)
-        return false;
+        return TriStateResult::NotSupported;
 
     int srcfd = d->nativeHandle();
     int dstfd = target->handle();
-    return QFileSystemEngine::cloneFile(srcfd, dstfd, d->metaData);
+    TriStateResult r = QFileSystemEngine::cloneFile(srcfd, dstfd, d->metaData);
+    if (r == TriStateResult::Failed)
+        setError(QFile::CopyError, qt_error_string(errno));
+    return r;
 }
 
 QT_END_NAMESPACE
diff --git a/src/corelib/io/qfsfileengine_win.cpp b/src/corelib/io/qfsfileengine_win.cpp
index bf8bb102d81..c436d4cd26b 100644
--- a/src/corelib/io/qfsfileengine_win.cpp
+++ b/src/corelib/io/qfsfileengine_win.cpp
@@ -897,12 +897,12 @@ bool QFSFileEnginePrivate::unmap(uchar *ptr)
 /*!
     \reimp
 */
-bool QFSFileEngine::cloneTo(QAbstractFileEngine *target)
+QAbstractFileEngine::TriStateResult QFSFileEngine::cloneTo(QAbstractFileEngine *target)
 {
     // There's some Windows Server 2016 API, but we won't
     // bother with it.
     Q_UNUSED(target);
-    return false;
+    return TriStateResult::NotSupported;
 }
 
 QT_END_NAMESPACE