internxt: handle file size limit errors during uploads

backend/internxt/internxt.go

@@ -1008,6 +1008,10 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 				o.restoreBackupFile(ctx, backupUUID, origName, origType)
 				return fs.ErrorCantUploadEmptyFiles
 			}
+			if tooLarge := fileTooLargeError(uploadErr); tooLarge != nil {
+				o.restoreBackupFile(ctx, backupUUID, origName, origType)
+				return o.f.tooLargeError(remote, tooLarge)
+			}
 			o.restoreBackupFile(ctx, backupUUID, origName, origType)
 			return uploadErr
 		}
@@ -1033,6 +1037,11 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 			return fs.ErrorCantUploadEmptyFiles
 		}
 
+		if tooLarge := fileTooLargeError(err); tooLarge != nil {
+			o.restoreBackupFile(ctx, backupUUID, origName, origType)
+			return o.f.tooLargeError(remote, tooLarge)
+		}
+
 		if err != nil {
 			meta, err = o.recoverFromTimeoutConflict(ctx, err, remote, dirID)
 		}
@@ -1105,6 +1114,25 @@ func isEmptyFileLimitError(err error) bool {
 		strings.Contains(errMsg, "you can not have empty files")
 }
 
+// fileTooLargeError extracts the SDK's FileTooLargeError from a wrapped error
+// chain, returning it (or nil) so callers can branch on the size limit.
+func fileTooLargeError(err error) *sdkerrors.FileTooLargeError {
+	var tooLarge *sdkerrors.FileTooLargeError
+	if errors.As(err, &tooLarge) {
+		return tooLarge
+	}
+	return nil
+}
+
+// tooLargeError formats a per-file, non-retryable error for the sync engine.
+// fserrors.NoRetryError signals "skip this file but continue the sync."
+func (f *Fs) tooLargeError(remote string, tooLarge *sdkerrors.FileTooLargeError) error {
+	return fserrors.NoRetryError(fmt.Errorf("%s: file size %s exceeds account upload limit of %s",
+		remote,
+		fs.SizeSuffix(tooLarge.Size),
+		fs.SizeSuffix(tooLarge.MaxSize)))
+}
+
 // recoverFromTimeoutConflict attempts to recover from a timeout or conflict error
 func (o *Object) recoverFromTimeoutConflict(ctx context.Context, uploadErr error, remote, dirID string) (*buckets.CreateMetaResponse, error) {
 	if !isTimeoutError(uploadErr) && !isConflictError(uploadErr) {

backend/internxt/upload.go

@@ -114,6 +114,9 @@ func (f *Fs) OpenChunkWriter(ctx context.Context, remote string, src fs.ObjectIn
 		return f.shouldRetry(ctx, err)
 	})
 	if err != nil {
+		if tooLarge := fileTooLargeError(err); tooLarge != nil {
+			return info, nil, f.tooLargeError(remote, tooLarge)
+		}
 		return info, nil, fmt.Errorf("failed to create upload session: %w", err)
 	}
 

fstest/test_all/config.yaml

@@ -686,6 +686,7 @@ backends:
  - backend: "internxt"
    remote: "TestInternxt:"
    fastlist: false
+   extratime: 2.0
    listretries: 5
    ignore:
      - TestRWFileHandleWriteNoWrite