diff --git a/vfs/vfscache/downloaders/downloaders.go b/vfs/vfscache/downloaders/downloaders.go
index 39cd4e883..6e37adfcb 100644
--- a/vfs/vfscache/downloaders/downloaders.go
+++ b/vfs/vfscache/downloaders/downloaders.go
@@ -457,15 +457,18 @@ func (dl *downloader) Write(p []byte) (n int, err error) {
 	// defer log.Trace(dl.dls.src, "p_len=%d", len(p))("n=%d, err=%v", &n, &err)
 
 	// Kick the waiters on exit if some characters received
+	//
+	// Only logs kickWaiters failures rather than returning them as this
+	// Write's own error: kickWaiters can return the downloaders' stale
+	// accumulated lastErr, which would otherwise fail this write (even
+	// when it succeeded) and get wrapped again by download(), growing
+	// unboundedly on every subsequent call while lastErr stays set.
 	defer func() {
 		if n <= 0 {
 			return
 		}
 		if waitErr := dl.dls.kickWaiters(); waitErr != nil {
 			fs.Errorf(dl.dls.src, "vfs cache: download write: failed to kick waiters: %v", waitErr)
-			if err == nil {
-				err = waitErr
-			}
 		}
 	}()
 
diff --git a/vfs/vfscache/downloaders/downloaders_test.go b/vfs/vfscache/downloaders/downloaders_test.go
index 592c3f470..7ad626927 100644
--- a/vfs/vfscache/downloaders/downloaders_test.go
+++ b/vfs/vfscache/downloaders/downloaders_test.go
@@ -2,6 +2,8 @@ package downloaders
 
 import (
 	"context"
+	"errors"
+	"fmt"
 	"io"
 	"sync"
 	"testing"
@@ -151,4 +153,43 @@ func TestDownloaders(t *testing.T) {
 			t.Fatal("Download did not return: the waiter was never dispatched")
 		}
 	})
+
+	// A successful write must not be turned into a failure by a stale
+	// error left over from a previous problem (e.g. the cache running
+	// out of space earlier). Regression test: this used to make Write
+	// return dls.lastErr even when the write itself succeeded, which
+	// then got wrapped again by download() and stored back as the new
+	// lastErr - causing the wrapped error message to grow without bound
+	// on every subsequent write.
+	t.Run("WriteDoesNotFailOnStaleError", func(t *testing.T) {
+		item, dls := newTest()
+		defer cancel(dls)
+
+		dls.mu.Lock()
+		dls.errorCount = maxErrorCount + 1
+		dls.lastErr = fmt.Errorf("vfs reader: failed to write to cache file: %w", errors.New("no space left on device"))
+		// A waiter for a range that isn't downloaded yet, so kickWaiters
+		// doesn't dispatch it immediately and reaches the errorCount check.
+		dls.waiters = append(dls.waiters, waiter{
+			r:       ranges.Range{Pos: 10 * 1024 * 1024, Size: 250},
+			errChan: make(chan error, 1),
+		})
+		dls.mu.Unlock()
+
+		dl := &downloader{
+			dls:       dls,
+			quit:      make(chan struct{}),
+			kick:      make(chan struct{}, 1),
+			offset:    0,
+			maxOffset: 1024,
+		}
+
+		p := make([]byte, 16)
+		_, err := io.ReadFull(readers.NewPatternReader(item.size), p)
+		require.NoError(t, err)
+
+		n, err := dl.Write(p)
+		require.NoError(t, err, "a successful write must not fail due to unrelated stale state")
+		assert.Equal(t, len(p), n)
+	})
 }