diff --git a/ompi/mca/coll/ucc/coll_ucc_allgather.c b/ompi/mca/coll/ucc/coll_ucc_allgather.c
index 776109c8fd2..c80aebb2a2c 100644
--- a/ompi/mca/coll/ucc/coll_ucc_allgather.c
+++ b/ompi/mca/coll/ucc/coll_ucc_allgather.c
@@ -15,15 +15,20 @@ static inline ucc_status_t mca_coll_ucc_allgather_init(const void *sbuf, size_t
                                                        ucc_coll_req_h *req,
                                                        mca_coll_ucc_req_t *coll_req)
 {
-    ucc_datatype_t         ucc_sdt, ucc_rdt;
+    ucc_datatype_t ucc_sdt = UCC_DT_INT8, ucc_rdt = UCC_DT_INT8;
+    bool is_inplace = (MPI_IN_PLACE == sbuf);
     int comm_size = ompi_comm_size(ucc_module->comm);
 
-    if (!ompi_datatype_is_contiguous_memory_layout(sdtype, scount) ||
+    if (!(is_inplace || ompi_datatype_is_contiguous_memory_layout(sdtype, scount)) ||
         !ompi_datatype_is_contiguous_memory_layout(rdtype, rcount * comm_size)) {
         goto fallback;
     }
-    ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
+
     ucc_rdt = ompi_dtype_to_ucc_dtype(rdtype);
+    if (!is_inplace) {
+        ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
+    }
+
     if (COLL_UCC_DT_UNSUPPORTED == ucc_sdt ||
         COLL_UCC_DT_UNSUPPORTED == ucc_rdt) {
         UCC_VERBOSE(5, "ompi_datatype is not supported: dtype = %s",
@@ -50,7 +55,7 @@ static inline ucc_status_t mca_coll_ucc_allgather_init(const void *sbuf, size_t
         }
     };
 
-    if (MPI_IN_PLACE == sbuf) {
+    if (is_inplace) {
         coll.mask  = UCC_COLL_ARGS_FIELD_FLAGS;
         coll.flags = UCC_COLL_ARGS_FLAG_IN_PLACE;
     }
diff --git a/ompi/mca/coll/ucc/coll_ucc_allgatherv.c b/ompi/mca/coll/ucc/coll_ucc_allgatherv.c
index 8652a360eb8..1a3ba27f053 100644
--- a/ompi/mca/coll/ucc/coll_ucc_allgatherv.c
+++ b/ompi/mca/coll/ucc/coll_ucc_allgatherv.c
@@ -17,10 +17,14 @@ static inline ucc_status_t mca_coll_ucc_allgatherv_init(const void *sbuf, size_t
                                                         ucc_coll_req_h *req,
                                                         mca_coll_ucc_req_t *coll_req)
 {
-    ucc_datatype_t         ucc_sdt, ucc_rdt;
+    ucc_datatype_t ucc_sdt = UCC_DT_INT8, ucc_rdt = UCC_DT_INT8;
+    bool is_inplace = (MPI_IN_PLACE == sbuf);
 
-    ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
     ucc_rdt = ompi_dtype_to_ucc_dtype(rdtype);
+    if (!is_inplace) {
+        ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
+    }
+    
     if (COLL_UCC_DT_UNSUPPORTED == ucc_sdt ||
         COLL_UCC_DT_UNSUPPORTED == ucc_rdt) {
         UCC_VERBOSE(5, "ompi_datatype is not supported: dtype = %s",
@@ -48,7 +52,7 @@ static inline ucc_status_t mca_coll_ucc_allgatherv_init(const void *sbuf, size_t
         }
     };
 
-    if (MPI_IN_PLACE == sbuf) {
+    if (is_inplace) {
         coll.mask  = UCC_COLL_ARGS_FIELD_FLAGS;
         coll.flags = UCC_COLL_ARGS_FLAG_IN_PLACE;
     }
diff --git a/ompi/mca/coll/ucc/coll_ucc_alltoall.c b/ompi/mca/coll/ucc/coll_ucc_alltoall.c
index 6b921033a57..1fce7b1f733 100644
--- a/ompi/mca/coll/ucc/coll_ucc_alltoall.c
+++ b/ompi/mca/coll/ucc/coll_ucc_alltoall.c
@@ -15,15 +15,20 @@ static inline ucc_status_t mca_coll_ucc_alltoall_init(const void *sbuf, size_t s
                                                       ucc_coll_req_h *req,
                                                       mca_coll_ucc_req_t *coll_req)
 {
-    ucc_datatype_t         ucc_sdt, ucc_rdt;
+    ucc_datatype_t ucc_sdt = UCC_DT_INT8, ucc_rdt = UCC_DT_INT8;
+    bool is_inplace = (MPI_IN_PLACE == sbuf);
     int comm_size = ompi_comm_size(ucc_module->comm);
 
-    if (!ompi_datatype_is_contiguous_memory_layout(sdtype, scount * comm_size) ||
+    if (!(is_inplace || ompi_datatype_is_contiguous_memory_layout(sdtype, scount * comm_size)) ||
         !ompi_datatype_is_contiguous_memory_layout(rdtype, rcount * comm_size)) {
         goto fallback;
     }
-    ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
+
     ucc_rdt = ompi_dtype_to_ucc_dtype(rdtype);
+    if (!is_inplace) {
+        ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
+    }
+
     if (COLL_UCC_DT_UNSUPPORTED == ucc_sdt ||
         COLL_UCC_DT_UNSUPPORTED == ucc_rdt) {
         UCC_VERBOSE(5, "ompi_datatype is not supported: dtype = %s",
@@ -50,7 +55,7 @@ static inline ucc_status_t mca_coll_ucc_alltoall_init(const void *sbuf, size_t s
         }
     };
 
-    if (MPI_IN_PLACE == sbuf) {
+    if (is_inplace) {
         coll.mask  = UCC_COLL_ARGS_FIELD_FLAGS;
         coll.flags = UCC_COLL_ARGS_FLAG_IN_PLACE;
     }
diff --git a/ompi/mca/coll/ucc/coll_ucc_alltoallv.c b/ompi/mca/coll/ucc/coll_ucc_alltoallv.c
index 06ea98adfe2..53fd0cfa4d7 100644
--- a/ompi/mca/coll/ucc/coll_ucc_alltoallv.c
+++ b/ompi/mca/coll/ucc/coll_ucc_alltoallv.c
@@ -17,10 +17,14 @@ static inline ucc_status_t mca_coll_ucc_alltoallv_init(const void *sbuf, const i
                                                        ucc_coll_req_h *req,
                                                        mca_coll_ucc_req_t *coll_req)
 {
-    ucc_datatype_t         ucc_sdt, ucc_rdt;
+    ucc_datatype_t ucc_sdt = UCC_DT_INT8, ucc_rdt = UCC_DT_INT8;
+    bool is_inplace = (MPI_IN_PLACE == sbuf);
 
-    ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
     ucc_rdt = ompi_dtype_to_ucc_dtype(rdtype);
+    if (!is_inplace) {
+        ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
+    }
+    
     if (COLL_UCC_DT_UNSUPPORTED == ucc_sdt ||
         COLL_UCC_DT_UNSUPPORTED == ucc_rdt) {
         UCC_VERBOSE(5, "ompi_datatype is not supported: dtype = %s",
@@ -49,7 +53,7 @@ static inline ucc_status_t mca_coll_ucc_alltoallv_init(const void *sbuf, const i
         }
     };
 
-    if (MPI_IN_PLACE == sbuf) {
+    if (is_inplace) {
         coll.mask  = UCC_COLL_ARGS_FIELD_FLAGS;
         coll.flags = UCC_COLL_ARGS_FLAG_IN_PLACE;
     }
diff --git a/ompi/mca/coll/ucc/coll_ucc_gather.c b/ompi/mca/coll/ucc/coll_ucc_gather.c
index f74dc25d8a0..8ede6a58e58 100644
--- a/ompi/mca/coll/ucc/coll_ucc_gather.c
+++ b/ompi/mca/coll/ucc/coll_ucc_gather.c
@@ -17,27 +17,35 @@ ucc_status_t mca_coll_ucc_gather_init(const void *sbuf, size_t scount, struct om
                                       ucc_coll_req_h *req,
                                       mca_coll_ucc_req_t *coll_req)
 {
-    ucc_datatype_t ucc_sdt, ucc_rdt;
+    ucc_datatype_t ucc_sdt = UCC_DT_INT8, ucc_rdt = UCC_DT_INT8;
+    bool is_inplace = (MPI_IN_PLACE == sbuf);
     int comm_rank = ompi_comm_rank(ucc_module->comm);
     int comm_size = ompi_comm_size(ucc_module->comm);
 
-    if (!ompi_datatype_is_contiguous_memory_layout(sdtype, scount)) {
-        goto fallback;
-    }
-    ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
     if (comm_rank == root) {
-        if (!ompi_datatype_is_contiguous_memory_layout(rdtype, rcount * comm_size)) {
+        if (!(is_inplace || ompi_datatype_is_contiguous_memory_layout(sdtype, scount)) ||
+            !ompi_datatype_is_contiguous_memory_layout(rdtype, rcount * comm_size)) {
             goto fallback;
         }
+
         ucc_rdt = ompi_dtype_to_ucc_dtype(rdtype);
-        if ((COLL_UCC_DT_UNSUPPORTED == ucc_rdt) ||
-            (MPI_IN_PLACE != sbuf && COLL_UCC_DT_UNSUPPORTED == ucc_sdt)) {
+        if (!is_inplace) {
+            ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
+        }
+
+        if ((COLL_UCC_DT_UNSUPPORTED == ucc_sdt) ||
+            (COLL_UCC_DT_UNSUPPORTED == ucc_rdt)) {
             UCC_VERBOSE(5, "ompi_datatype is not supported: dtype = %s",
-                        (COLL_UCC_DT_UNSUPPORTED == ucc_rdt) ?
-                        rdtype->super.name : sdtype->super.name);
+                        (COLL_UCC_DT_UNSUPPORTED == ucc_sdt) ?
+                        sdtype->super.name : rdtype->super.name);
             goto fallback;
         }
     } else {
+        if (!ompi_datatype_is_contiguous_memory_layout(sdtype, scount)) {
+            goto fallback;
+        }
+
+        ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
         if (COLL_UCC_DT_UNSUPPORTED == ucc_sdt) {
             UCC_VERBOSE(5, "ompi_datatype is not supported: dtype = %s",
                         sdtype->super.name);
@@ -64,7 +72,7 @@ ucc_status_t mca_coll_ucc_gather_init(const void *sbuf, size_t scount, struct om
         },
     };
 
-    if (MPI_IN_PLACE == sbuf) {
+    if (is_inplace) {
         coll.mask |= UCC_COLL_ARGS_FIELD_FLAGS;
         coll.flags = UCC_COLL_ARGS_FLAG_IN_PLACE;
     }
diff --git a/ompi/mca/coll/ucc/coll_ucc_gatherv.c b/ompi/mca/coll/ucc/coll_ucc_gatherv.c
index 15023698ffa..13049a76e0f 100644
--- a/ompi/mca/coll/ucc/coll_ucc_gatherv.c
+++ b/ompi/mca/coll/ucc/coll_ucc_gatherv.c
@@ -17,20 +17,24 @@ static inline ucc_status_t mca_coll_ucc_gatherv_init(const void *sbuf, size_t sc
                                                      ucc_coll_req_h *req,
                                                      mca_coll_ucc_req_t *coll_req)
 {
-    ucc_datatype_t ucc_sdt, ucc_rdt;
+    ucc_datatype_t ucc_sdt = UCC_DT_INT8, ucc_rdt = UCC_DT_INT8;
+    bool is_inplace = (MPI_IN_PLACE == sbuf);
     int comm_rank = ompi_comm_rank(ucc_module->comm);
 
-    ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
     if (comm_rank == root) {
         ucc_rdt = ompi_dtype_to_ucc_dtype(rdtype);
-        if ((COLL_UCC_DT_UNSUPPORTED == ucc_rdt) ||
-            (MPI_IN_PLACE != sbuf && COLL_UCC_DT_UNSUPPORTED == ucc_sdt)) {
+        if (!is_inplace) {
+            ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
+        }
+        if ((COLL_UCC_DT_UNSUPPORTED == ucc_sdt) ||
+            (COLL_UCC_DT_UNSUPPORTED == ucc_rdt)) {
             UCC_VERBOSE(5, "ompi_datatype is not supported: dtype = %s",
-                        (COLL_UCC_DT_UNSUPPORTED == ucc_rdt) ?
-                        rdtype->super.name : sdtype->super.name);
+                        (COLL_UCC_DT_UNSUPPORTED == ucc_sdt) ?
+                        sdtype->super.name : rdtype->super.name);
             goto fallback;
         }
     } else {
+        ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
         if (COLL_UCC_DT_UNSUPPORTED == ucc_sdt) {
             UCC_VERBOSE(5, "ompi_datatype is not supported: dtype = %s",
                         sdtype->super.name);
@@ -58,7 +62,7 @@ static inline ucc_status_t mca_coll_ucc_gatherv_init(const void *sbuf, size_t sc
         },
     };
 
-    if (MPI_IN_PLACE == sbuf) {
+    if (is_inplace) {
         coll.mask |= UCC_COLL_ARGS_FIELD_FLAGS;
         coll.flags = UCC_COLL_ARGS_FLAG_IN_PLACE;
     }
diff --git a/ompi/mca/coll/ucc/coll_ucc_scatter.c b/ompi/mca/coll/ucc/coll_ucc_scatter.c
index 6154e820b40..548ce290bdf 100644
--- a/ompi/mca/coll/ucc/coll_ucc_scatter.c
+++ b/ompi/mca/coll/ucc/coll_ucc_scatter.c
@@ -18,21 +18,35 @@ ucc_status_t mca_coll_ucc_scatter_init(const void *sbuf, size_t scount,
                                        ucc_coll_req_h *req,
                                        mca_coll_ucc_req_t *coll_req)
 {
-    ucc_datatype_t ucc_sdt, ucc_rdt;
+    ucc_datatype_t ucc_sdt = UCC_DT_INT8, ucc_rdt = UCC_DT_INT8;
+    bool is_inplace = (MPI_IN_PLACE == rbuf);
     int comm_rank = ompi_comm_rank(ucc_module->comm);
     int comm_size = ompi_comm_size(ucc_module->comm);
 
-    ucc_rdt = ompi_dtype_to_ucc_dtype(rdtype);
     if (comm_rank == root) {
+        if (!(is_inplace || ompi_datatype_is_contiguous_memory_layout(rdtype, rcount)) ||
+            !ompi_datatype_is_contiguous_memory_layout(sdtype, scount * comm_size)) {
+            goto fallback;
+        }
+
         ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
+        if (!is_inplace) {
+            ucc_rdt = ompi_dtype_to_ucc_dtype(rdtype);
+        }
+
         if ((COLL_UCC_DT_UNSUPPORTED == ucc_sdt) ||
-            (MPI_IN_PLACE != rbuf && COLL_UCC_DT_UNSUPPORTED == ucc_rdt)) {
+            (COLL_UCC_DT_UNSUPPORTED == ucc_rdt)) {
             UCC_VERBOSE(5, "ompi_datatype is not supported: dtype = %s",
                         (COLL_UCC_DT_UNSUPPORTED == ucc_sdt) ?
                         sdtype->super.name : rdtype->super.name);
             goto fallback;
         }
     } else {
+        if (!ompi_datatype_is_contiguous_memory_layout(rdtype, rcount)) {
+            goto fallback;
+        }
+
+        ucc_rdt = ompi_dtype_to_ucc_dtype(rdtype);
         if (COLL_UCC_DT_UNSUPPORTED == ucc_rdt) {
             UCC_VERBOSE(5, "ompi_datatype is not supported: dtype = %s",
                         rdtype->super.name);
@@ -59,7 +73,7 @@ ucc_status_t mca_coll_ucc_scatter_init(const void *sbuf, size_t scount,
         },
     };
 
-    if (MPI_IN_PLACE == rbuf) {
+    if (is_inplace) {
         coll.mask |= UCC_COLL_ARGS_FIELD_FLAGS;
         coll.flags = UCC_COLL_ARGS_FLAG_IN_PLACE;
     }
diff --git a/ompi/mca/coll/ucc/coll_ucc_scatterv.c b/ompi/mca/coll/ucc/coll_ucc_scatterv.c
index 848508e8bc6..738aa14a953 100644
--- a/ompi/mca/coll/ucc/coll_ucc_scatterv.c
+++ b/ompi/mca/coll/ucc/coll_ucc_scatterv.c
@@ -18,22 +18,25 @@ ucc_status_t mca_coll_ucc_scatterv_init(const void *sbuf, const int *scounts,
                                         ucc_coll_req_h *req,
                                         mca_coll_ucc_req_t *coll_req)
 {
-    ucc_datatype_t ucc_sdt, ucc_rdt;
+    ucc_datatype_t ucc_sdt = UCC_DT_INT8, ucc_rdt = UCC_DT_INT8;
+    bool is_inplace = (MPI_IN_PLACE == rbuf);
     int comm_rank = ompi_comm_rank(ucc_module->comm);
-    int comm_size = ompi_comm_size(ucc_module->comm);
 
-    ucc_rdt = ompi_dtype_to_ucc_dtype(rdtype);
     if (comm_rank == root) {
         ucc_sdt = ompi_dtype_to_ucc_dtype(sdtype);
+        if (!is_inplace) {
+            ucc_rdt = ompi_dtype_to_ucc_dtype(rdtype);
+        }
+
         if ((COLL_UCC_DT_UNSUPPORTED == ucc_sdt) ||
-            (MPI_IN_PLACE != rbuf && COLL_UCC_DT_UNSUPPORTED == ucc_rdt)) {
+            (COLL_UCC_DT_UNSUPPORTED == ucc_rdt)) {
             UCC_VERBOSE(5, "ompi_datatype is not supported: dtype = %s",
                         (COLL_UCC_DT_UNSUPPORTED == ucc_sdt) ?
                         sdtype->super.name : rdtype->super.name);
             goto fallback;
         }
-
     } else {
+        ucc_rdt = ompi_dtype_to_ucc_dtype(rdtype);
         if (COLL_UCC_DT_UNSUPPORTED == ucc_rdt) {
             UCC_VERBOSE(5, "ompi_datatype is not supported: dtype = %s",
                         rdtype->super.name);
@@ -61,7 +64,7 @@ ucc_status_t mca_coll_ucc_scatterv_init(const void *sbuf, const int *scounts,
         },
     };
 
-    if (MPI_IN_PLACE == rbuf) {
+    if (is_inplace) {
         coll.mask |= UCC_COLL_ARGS_FIELD_FLAGS;
         coll.flags = UCC_COLL_ARGS_FLAG_IN_PLACE;
     }