error : Error in as.POSIXlt.character(x, tz = tz(x)) : character string is not in a standard unambiguous format

[riawjddus12]

I want to make year, month variables.
But the error on the title still appears.
What can i do for this error? please help me. thank you.

install.packages("lubridate")

df_1 <- read_excel("guwoldong 2018.10~2019.09.xls")
df_2 <- read_excel("songhae 2018.10~2019.09.xls")
df_3 <- read_excel("unseo 2018.10~2019.09.xls")
df_123 <- bind_rows(df_1, df_2 df_3)

df_123$date <- month(df_123$date)
df_123$date <- year(df_123$date)

[andresrcs]

Can you please share a small part of the data set in a copy-paste friendly format?

In case you don't know how to do it, there are many options, which include:

1. If you have stored the data set in some R object, dput function is very handy.

2. In case the data set is in a spreadsheet, check out the datapasta package. Take a look at this link.