Warning messages: 1: Problem while computing `..1 = across(...)`. i unknown timezone '%m/%d/%Y'

[Zcythor]

I'm trying to convert two specific columns from %d-%m-%Y %H:%M:%S to just %d-%m-%Y but when I apply this code:

# Step 6.5: Change datetime format of date columns to date only
dfTranformedWithEmployeeProfile %>%
  mutate(across(c("Survey Sent Date", "Respondent Submission Date"), ~ as.Date(., format("%m/%d/%Y"))))

I get the following error:

1: Problem while computing `..1 = across(...)`.
i unknown timezone '%m/%d/%Y' 
2: Problem while computing `..1 = across(...)`.
i unknown timezone '%m/%d/%Y'

in which the column in question has all of its values replaced with NA.

this is the dataframe:

tibble::tribble(
  ~Survey.Sent.Date, ~Respondent.Submission.Date,
                 NA,                "08/08/2022",
                 NA,                "04/08/2022",
                 NA,                "04/08/2022",
                 NA,                "04/08/2022"
  )
#> # A tibble: 4 × 2
#>   Survey.Sent.Date Respondent.Submission.Date
#>   <lgl>            <chr>                     
#> 1 NA               08/08/2022                
#> 2 NA               04/08/2022                
#> 3 NA               04/08/2022                
#> 4 NA               04/08/2022

^{Created on 2022-09-15 by the reprex package (v2.0.1)}

tibble::tribble(
  ~Survey.Sent.Date, ~Respondent.Submission.Date,
                 NA,                "08/08/2022",
                 NA,                "04/08/2022",
                 NA,                "04/08/2022",
                 NA,                "04/08/2022"
  )

How I want it

#> # A tibble: 4 × 2
#>   Survey.Sent.Date Respondent.Submission.Date
#>   <lgl>             <chr>                     
#> 29/07/2022       08/08/2022                
#> 29/07/2022       04/08/2022                
#> 29/07/2022       04/08/2022                
#> 29/07/2022       04/08/2022

what is causing this problem and how do I fix it. I have tried using

dfTranformedWithEmployeeProfile$Survey Sent Date <- lubridate::mdy_hms(dfTranformedWithEmployeeProfile$Survey Sent Date, tz="Europe/London")

to fix this but it doesn't change anything.

[martin.R]

You probably just need to change the specified date format:

dfTranformedWithEmployeeProfile %>%
  mutate(across(c("Survey Sent Date", "Respondent Submission Date"), ~ as.Date(., format("%d/%m/%Y"))))