diff --git a/test/API/H5_api_dataset_test.c b/test/API/H5_api_dataset_test.c
index 4110dd714de..768ba490130 100644
--- a/test/API/H5_api_dataset_test.c
+++ b/test/API/H5_api_dataset_test.c
@@ -9805,27 +9805,49 @@ test_dataset_vlen_io(void)
         goto error;
     }
 
-    if ((dset_int = H5Dcreate2(file_id, DATASET_VLEN_IO_DSET_NAME "_int", vlen_int, space_id, H5P_DEFAULT,
-                               H5P_DEFAULT, H5P_DEFAULT)) < 0) {
+    if ((dset_int = H5Dcreate2(container_group, DATASET_VLEN_IO_DSET_NAME "_int", vlen_int, space_id,
+                               H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) {
         H5_FAILED();
         printf("    couldn't create dataset with vlen integer sequence datatype");
         goto error;
     }
 
-    if ((dset_float = H5Dcreate2(file_id, DATASET_VLEN_IO_DSET_NAME "_float", vlen_float, space_id,
+    if ((dset_float = H5Dcreate2(container_group, DATASET_VLEN_IO_DSET_NAME "_float", vlen_float, space_id,
                                  H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) {
         H5_FAILED();
         printf("    couldn't create dataset with vlen float sequence datatype");
         goto error;
     }
 
-    if ((dset_string = H5Dcreate2(file_id, DATASET_VLEN_IO_DSET_NAME "_string", vlen_string, space_id,
+    if ((dset_string = H5Dcreate2(container_group, DATASET_VLEN_IO_DSET_NAME "_string", vlen_string, space_id,
                                   H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0) {
         H5_FAILED();
         printf("    couldn't create dataset with vlen string sequence datatype");
         goto error;
     }
 
+    /* Close datasets until individual tests */
+    if (H5Dclose(dset_int) < 0) {
+        H5_FAILED();
+        printf("    couldn't close dataset with vlen integer sequence datatype");
+    }
+
+    dset_int = H5I_INVALID_HID;
+
+    if (H5Dclose(dset_float) < 0) {
+        H5_FAILED();
+        printf("    couldn't close dataset with vlen float sequence datatype");
+    }
+
+    dset_float = H5I_INVALID_HID;
+
+    if (H5Dclose(dset_string) < 0) {
+        H5_FAILED();
+        printf("    couldn't close dataset with vlen string sequence datatype");
+    }
+
+    dset_string = H5I_INVALID_HID;
+
     memset(wbuf, 0, sizeof(hvl_t) * DATASET_VLEN_IO_DSET_DIMS);
     memset(rbuf, 0, sizeof(hvl_t) * DATASET_VLEN_IO_DSET_DIMS);
 
@@ -9848,10 +9870,39 @@ test_dataset_vlen_io(void)
                 wbuf[i].len = i + 1;
             }
 
+            /* Open dataset */
+            if ((dset_int = H5Dopen2(container_group, DATASET_VLEN_IO_DSET_NAME "_int", H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_all_int);
+
             /* Perform write */
             if ((H5Dwrite(dset_int, vlen_int, space_id, H5S_ALL, H5P_DEFAULT, (const void *)wbuf)) < 0)
                 PART_TEST_ERROR(rw_all_int);
 
+            /* Close and reopen file objects to flush cache */
+            if (H5Dclose(dset_int) < 0)
+                PART_TEST_ERROR(rw_all_int);
+
+            dset_int = H5I_INVALID_HID;
+
+            if (H5Gclose(container_group) < 0)
+                PART_TEST_ERROR(rw_all_int);
+
+            container_group = H5I_INVALID_HID;
+
+            if (H5Fclose(file_id) < 0)
+                PART_TEST_ERROR(rw_all_int);
+
+            file_id = H5I_INVALID_HID;
+
+            if ((file_id = H5Fopen(H5_api_test_filename, H5F_ACC_RDWR, H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_all_int);
+
+            if ((container_group = H5Gopen(file_id, DATASET_TEST_GROUP_NAME, H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_all_int);
+
+            if ((dset_int = H5Dopen2(container_group, DATASET_VLEN_IO_DSET_NAME "_int", H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_all_int);
+
             /* Perform read */
             if ((H5Dread(dset_int, vlen_int, space_id, H5S_ALL, H5P_DEFAULT, (void *)rbuf)) < 0)
                 PART_TEST_ERROR(rw_all_int);
@@ -9869,10 +9920,13 @@ test_dataset_vlen_io(void)
                         PART_TEST_ERROR(rw_all_int);
             }
 
-            PASSED();
+            /* Close before use in selection tests */
+            if (H5Dclose(dset_int) < 0)
+                PART_TEST_ERROR(rw_all_int);
 
-            /* Reset buffers */
+            dset_int = H5I_INVALID_HID;
 
+            /* Reset buffers */
             if (H5Treclaim(vlen_int, space_id, H5P_DEFAULT, rbuf) < 0)
                 PART_TEST_ERROR(rw_all_int);
 
@@ -9881,8 +9935,11 @@ test_dataset_vlen_io(void)
 
             memset(wbuf, 0, sizeof(hvl_t) * DATASET_VLEN_IO_DSET_DIMS);
             memset(rbuf, 0, sizeof(hvl_t) * DATASET_VLEN_IO_DSET_DIMS);
+
+            PASSED();
         }
         PART_END(rw_all_int)
+        PART_BEGIN(rw_all_float)
         {
             TESTING_2("write and read entire dataspace with float sequence");
             /* Set up write buffer */
@@ -9897,10 +9954,39 @@ test_dataset_vlen_io(void)
                 wbuf[i].len = i + 1;
             }
 
+            /* Open dataset */
+            if ((dset_float = H5Dopen2(container_group, DATASET_VLEN_IO_DSET_NAME "_float", H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_all_float);
+
             /* Perform write */
             if ((H5Dwrite(dset_float, vlen_float, space_id, H5S_ALL, H5P_DEFAULT, (const void *)wbuf)) < 0)
                 PART_TEST_ERROR(rw_all_float);
 
+            /* Close and reopen file objects to flush cache */
+            if (H5Dclose(dset_float) < 0)
+                PART_TEST_ERROR(rw_all_float);
+
+            dset_float = H5I_INVALID_HID;
+
+            if (H5Gclose(container_group) < 0)
+                PART_TEST_ERROR(rw_all_float);
+
+            container_group = H5I_INVALID_HID;
+
+            if (H5Fclose(file_id) < 0)
+                PART_TEST_ERROR(rw_all_float);
+
+            file_id = H5I_INVALID_HID;
+
+            if ((file_id = H5Fopen(H5_api_test_filename, H5F_ACC_RDWR, H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_all_float);
+
+            if ((container_group = H5Gopen2(file_id, DATASET_TEST_GROUP_NAME, H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_all_float);
+
+            if ((dset_float = H5Dopen2(container_group, DATASET_VLEN_IO_DSET_NAME "_float", H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_all_float);
+
             /* Perform read */
             if ((H5Dread(dset_float, vlen_float, space_id, H5S_ALL, H5P_DEFAULT, (void *)rbuf)) < 0)
                 PART_TEST_ERROR(rw_all_float);
@@ -9922,8 +10008,6 @@ test_dataset_vlen_io(void)
                 }
             }
 
-            PASSED();
-
             /* Reset buffers */
 
             if (H5Treclaim(vlen_float, space_id, H5P_DEFAULT, rbuf) < 0)
@@ -9934,7 +10018,8 @@ test_dataset_vlen_io(void)
 
             memset(wbuf, 0, sizeof(hvl_t) * DATASET_VLEN_IO_DSET_DIMS);
             memset(rbuf, 0, sizeof(hvl_t) * DATASET_VLEN_IO_DSET_DIMS);
-            PART_BEGIN(rw_all_float)
+
+            PASSED();
         }
         PART_END(rw_all_float);
 
@@ -9954,10 +10039,41 @@ test_dataset_vlen_io(void)
                 wbuf[i].len = i + 1;
             }
 
+            /* Open the dataset */
+            if ((dset_string = H5Dopen2(container_group, DATASET_VLEN_IO_DSET_NAME "_string", H5P_DEFAULT)) <
+                0)
+                PART_TEST_ERROR(rw_all_string);
+
             /* Perform write */
             if ((H5Dwrite(dset_string, vlen_string, space_id, H5S_ALL, H5P_DEFAULT, (const void *)wbuf)) < 0)
                 PART_TEST_ERROR(rw_all_string);
 
+            /* Close and reopen file objects to flush cache */
+            if (H5Dclose(dset_string) < 0)
+                PART_TEST_ERROR(rw_all_string);
+
+            dset_string = H5I_INVALID_HID;
+
+            if (H5Gclose(container_group) < 0)
+                PART_TEST_ERROR(rw_all_string);
+
+            container_group = H5I_INVALID_HID;
+
+            if (H5Fclose(file_id) < 0)
+                PART_TEST_ERROR(rw_all_string);
+
+            file_id = H5I_INVALID_HID;
+
+            if ((file_id = H5Fopen(H5_api_test_filename, H5F_ACC_RDWR, H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_all_string);
+
+            if ((container_group = H5Gopen2(file_id, DATASET_TEST_GROUP_NAME, H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_all_string);
+
+            if ((dset_string = H5Dopen2(container_group, DATASET_VLEN_IO_DSET_NAME "_string", H5P_DEFAULT)) <
+                0)
+                PART_TEST_ERROR(rw_all_string);
+
             /* Perform read */
             if ((H5Dread(dset_string, vlen_string, space_id, H5S_ALL, H5P_DEFAULT, (void *)rbuf)) < 0)
                 PART_TEST_ERROR(rw_all_string);
@@ -9981,8 +10097,6 @@ test_dataset_vlen_io(void)
                 }
             }
 
-            PASSED();
-
             /* Reset buffers */
 
             if (H5Treclaim(vlen_string, space_id, H5P_DEFAULT, rbuf) < 0)
@@ -9993,6 +10107,8 @@ test_dataset_vlen_io(void)
 
             memset(wbuf, 0, sizeof(hvl_t) * DATASET_VLEN_IO_DSET_DIMS);
             memset(rbuf, 0, sizeof(hvl_t) * DATASET_VLEN_IO_DSET_DIMS);
+
+            PASSED();
         }
         PART_END(rw_all_string);
 
@@ -10019,10 +10135,36 @@ test_dataset_vlen_io(void)
                 wbuf[i].len = i + 1;
             }
 
+            /* Open dataset */
+            if ((dset_int = H5Dopen2(container_group, DATASET_VLEN_IO_DSET_NAME "_int", H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_point_selection);
+
             /* Perform write */
             if ((H5Dwrite(dset_int, vlen_int, space_id, space_id, H5P_DEFAULT, (const void *)wbuf)) < 0)
                 PART_TEST_ERROR(rw_point_selection);
 
+            /* Close and reopen file objects to flush cache */
+            if (H5Dclose(dset_int) < 0)
+                PART_TEST_ERROR(rw_point_selection);
+            dset_int = H5I_INVALID_HID;
+
+            if (H5Gclose(container_group) < 0)
+                PART_TEST_ERROR(rw_point_selection);
+            container_group = H5I_INVALID_HID;
+
+            if (H5Fclose(file_id) < 0)
+                PART_TEST_ERROR(rw_point_selection);
+            file_id = H5I_INVALID_HID;
+
+            if ((file_id = H5Fopen(H5_api_test_filename, H5F_ACC_RDWR, H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_point_selection);
+
+            if ((container_group = H5Gopen2(file_id, DATASET_TEST_GROUP_NAME, H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_point_selection);
+
+            if ((dset_int = H5Dopen2(container_group, DATASET_VLEN_IO_DSET_NAME "_int", H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_point_selection);
+
             /* Perform read */
             if ((H5Dread(dset_int, vlen_int, space_id, space_id, H5P_DEFAULT, (void *)rbuf)) < 0)
                 PART_TEST_ERROR(rw_point_selection);
@@ -10049,10 +10191,11 @@ test_dataset_vlen_io(void)
                 }
             }
 
-            PASSED();
+            if (H5Dclose(dset_int) < 0)
+                PART_TEST_ERROR(rw_point_selection);
+            dset_int = H5I_INVALID_HID;
 
             /* Reset buffers */
-
             if (H5Treclaim(vlen_int, space_id, H5P_DEFAULT, rbuf) < 0)
                 PART_TEST_ERROR(rw_point_selection);
 
@@ -10061,6 +10204,8 @@ test_dataset_vlen_io(void)
 
             memset(wbuf, 0, sizeof(hvl_t) * DATASET_VLEN_IO_DSET_DIMS);
             memset(rbuf, 0, sizeof(hvl_t) * DATASET_VLEN_IO_DSET_DIMS);
+
+            PASSED();
         }
         PART_END(rw_point_selection);
 
@@ -10087,10 +10232,36 @@ test_dataset_vlen_io(void)
                 wbuf[i].len = i + 1;
             }
 
+            /* Open dataset */
+            if ((dset_int = H5Dopen2(container_group, DATASET_VLEN_IO_DSET_NAME "_int", H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_hyperslab_selection);
+
             /* Perform write */
             if ((H5Dwrite(dset_int, vlen_int, space_id, space_id, H5P_DEFAULT, (const void *)wbuf)) < 0)
                 PART_TEST_ERROR(rw_hyperslab_selection);
 
+            /* Close and reopen file objects to flush cache */
+            if (H5Dclose(dset_int) < 0)
+                PART_TEST_ERROR(rw_hyperslab_selection);
+            dset_int = H5I_INVALID_HID;
+
+            if (H5Gclose(container_group) < 0)
+                PART_TEST_ERROR(rw_hyperslab_selection);
+            container_group = H5I_INVALID_HID;
+
+            if (H5Fclose(file_id) < 0)
+                PART_TEST_ERROR(rw_hyperslab_selection);
+            file_id = H5I_INVALID_HID;
+
+            if ((file_id = H5Fopen(H5_api_test_filename, H5F_ACC_RDWR, H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_hyperslab_selection);
+
+            if ((container_group = H5Gopen2(file_id, DATASET_TEST_GROUP_NAME, H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_hyperslab_selection);
+
+            if ((dset_int = H5Dopen2(container_group, DATASET_VLEN_IO_DSET_NAME "_int", H5P_DEFAULT)) < 0)
+                PART_TEST_ERROR(rw_hyperslab_selection);
+
             /* Perform read */
             if ((H5Dread(dset_int, vlen_int, space_id, space_id, H5P_DEFAULT, (void *)rbuf)) < 0)
                 PART_TEST_ERROR(rw_hyperslab_selection);
@@ -10117,10 +10288,7 @@ test_dataset_vlen_io(void)
                 }
             }
 
-            PASSED();
-
             /* Reset buffers */
-
             if (H5Treclaim(vlen_int, space_id, H5P_DEFAULT, rbuf) < 0)
                 PART_TEST_ERROR(rw_hyperslab_selection);
 
@@ -10129,6 +10297,8 @@ test_dataset_vlen_io(void)
 
             memset(wbuf, 0, sizeof(hvl_t) * DATASET_VLEN_IO_DSET_DIMS);
             memset(rbuf, 0, sizeof(hvl_t) * DATASET_VLEN_IO_DSET_DIMS);
+
+            PASSED();
         }
         PART_END(rw_hyperslab_selection);
     }