This is because the R language default behavior is a unique identifier

Duplicate lines need to be removed

This is very common in differential expression, because different IDs may correspond to the same gene_ symbol

genes_sig <- res_sig %>% 
  arrange(adj.P.Val) %>% #Sort by Pvalue from smallest to largest
  as tibble() %>%
  column_to_rownames(var = "gene_symbol")

report errors

Error in `.rowNamesDF<-`(x, value = value) : 
  duplicate 'row.names' are not allowed
In addition: Warning message:
non-unique values when setting 'row.names': ‘’, ‘ AMY2A ’, ‘ ANKRD20A3 ’, ‘ ANXA8 ’, ‘ AQP12B ’, ‘ AREG ’, ‘ ARHGDIG ’, ‘ CLIC1 ’, ‘ CTRB2 ’, ‘ DPCR1 ’, ‘ FAM72B ’, ‘ FCGR3A ’, ‘ FER1L4 ’, ‘ HBA2 ’, ‘ HIST1H4I ’, ‘ HIST2H2AA4 ’, ‘ KRT17P2 ’, ‘ KRT6A ’, ‘ LOC101059935 ’, ‘ MRC1 ’, ‘ MT-TD ’, ‘ MT-TV ’, ‘ NPR3 ’, ‘ NRP2 ’, ‘ PGA3 ’, ‘ PRSS2 ’, ‘ REEP3 ’, ‘ RNU6-776P ’, ‘ SFTA2 ’, ‘ SLC44A4 ’, ‘ SNORD116-3 ’, ‘ SNORD116-5 ’, ‘ SORBS2 ’, ‘ TNXB ’, ‘ TRIM31 ’, ‘ UGT2B15 ’ 

Try to use the duplicated() function

res_df = res_df[!duplicated(res_df),] %>% as.tibble() %>%
column_to_rownames(var = "gene_symbol") 

Still not?Duplicated removing duplicate values still shows that duplicate values exist

Error in `.rowNamesDF<-`(x, value = value) : 
  duplicate 'row.names' are not allowed
In addition: Warning message:
non-unique values when setting 'row.names': ‘ AMY2A ’, ‘ ANKRD20A3 ’, ‘ ANXA8 ’, ‘ AQP12B ’, ‘ AREG ’, ‘ ARHGDIG ’, ‘ CLIC1 ’, ‘ CTRB2 ’, ‘ DPCR1 ’, ‘ FAM72B ’, ‘ FCGR3A ’, ‘ FER1L4 ’, ‘ HIST1H4I ’, ‘ HIST2H2AA4 ’, ‘ KRT17P2 ’, ‘ KRT6A ’, ‘ LOC101059935 ’, ‘ MT-TD ’, ‘ MT-TV ’, ‘ NPR3 ’, ‘ NRP2 ’, ‘ PGA3 ’, ‘ PRSS2 ’, ‘ REEP3 ’, ‘ RNU6-776P ’, ‘ SFTA2 ’, ‘ SORBS2 ’, ‘ TRIM31 ’, ‘ UGT2B15 ’ 

Another way is to use the uniqe function of the dyplr package

res_df = res_df %>% distinct(gene_symbol,.keep_all = T) %>% as.tibble() %>%
  column_to_rownames(var = "gene_symbol") 

Successfully solved