diff --git a/R/NcDataReader.R b/R/NcDataReader.R
index 741ffbb6d1ca54f4e1e224df04feddefef9682fb..ebc58fc27c6a6c5a379e9773de1ffe27bed2ecc3 100644
--- a/R/NcDataReader.R
+++ b/R/NcDataReader.R
@@ -221,6 +221,13 @@ NcDataReader <- function(file_path = NULL, file_object = NULL,
           # Origin year and month
           ori_year <- as.numeric(substr(parts[2], 1, 4))
           ori_month <- as.numeric(substr(parts[2], 6, 7))
+          if (is.na(ori_month)) {
+            ori_month <- as.numeric(substr(parts[2], 6, 6)) 
+          }
+          if (!is.numeric(ori_year) | !is.numeric(ori_month)) {
+            stop(paste0("The time unit attribute format is not 'YYYY-MM-DD' or 'YYYY-M-D'. ",
+                        "Check the file or contact the maintainer."))
+          }
 
           if (calendar == 'gregorian') {
             # Find how many years + months 
diff --git a/R/Start.R b/R/Start.R
index 3d82d57e6b711b9c3c4785b532a38d617006a37b..e8a1d7df40a55151e6329c8bb7707bde3beaf6da 100644
--- a/R/Start.R
+++ b/R/Start.R
@@ -3654,6 +3654,9 @@ Start <- function(..., # dim = indices/selectors,
       }
     }
   }
+  #=========================================================================
+  # Find the dimension to split if split_multiselected_dims = TRUE.
+  # If there is no dimension able to be split, change split_multiselected_dims to FALSE.
   all_split_dims <- NULL
   if (split_multiselected_dims) {
     for (dim_param in 1:length(dim_params)) {
@@ -3692,7 +3695,13 @@ Start <- function(..., # dim = indices/selectors,
         }
       }
     }
+    if (is.null(all_split_dims)) {
+      split_multiselected_dims <- FALSE
+      .warning(paste0("Not found any dimensions able to be split. The parameter ",
+                      "'split_multiselected_dims' is changed to FALSE."))
+    }
   }
+  #======================================================================
 
   if (merge_across_dims_narm) {
     # only merge_across_dims -> the 'time' dim length needs to be adjusted
@@ -3746,6 +3755,7 @@ Start <- function(..., # dim = indices/selectors,
   if (split_multiselected_dims & merge_across_dims) {
     # TODO: More than one split?
     inner_dim_pos_in_split_dims <- which(names(all_split_dims[[1]]) == inner_dims_across_files)  
+
     # if inner_dim is not the first, change!
     if (inner_dim_pos_in_split_dims != 1) {
       split_dims <- c(split_dims[inner_dim_pos_in_split_dims],
diff --git a/tests/testthat/test-Start-split-merge.R b/tests/testthat/test-Start-split-merge.R
index 10e8ab671c8207acac694cc467fd22ac5a438e45..da21f9233c063f9cb4c8b334057bf3419ee12bd8 100644
--- a/tests/testthat/test-Start-split-merge.R
+++ b/tests/testthat/test-Start-split-merge.R
@@ -4,6 +4,7 @@ context("Start() split + merge dim and value check")
 
 var_name <- 'sfcWind'
 path.exp <- '/esarchive/exp/ecmwf/s2s-monthly_ensforhc/daily/$var$_f24h/$sdate$/$var$_$syear$.nc'
+
 suppressWarnings(
 hcst <- Start(dat = path.exp,
               var =  var_name,