Solving Error: 'C:\U' used without hex digits in character string starting 'C:\U' when Reading R Files or Changing Paths

If you only seek a solution, you might only need to see how to fix it, but if you don’t want to encounter the same error again, it is recommended to read everything.

Error

Diagnosis

For instance, when trying to read an example.csv file on the desktop as shown above, the following error may occur.

Error: '\U' used without hex digits in character string starting ""C:\U"

Despite looking over all the paths and finding no issue, you might have tried changing the path suspecting the Korean word ‘Desktop’ to be the problem. However, unless moving right under the C: or D: drive, similar issues continue to occur.

Reason

The indirect reason for the problem is that the file was placed on the desktop, which led to entering the Users folder. Possibly, when copying and pasting from the explorer’s address bar directly, \U was read in hexadecimal, causing an error. It recognizes as an escape character when something follows \, causing problems. The reason why we specifically target \U in this post title is because many R beginners are likely to start working from the desktop without much thought and see this message.

Escape characters exist to represent things that are difficult to leave in a string by keyboard input, such as hitting the enter key, the current time, or backspace. So, normally, the backslash, the currency symbol \, is used to prevent accidental use by entering a specific letter after it. (The computer recognizes \ and backslash as the same. If it’s hard to understand, you can just memorize it.)

Ironically, because backslashes are used for such purposes, it can be confusing whether one wants to use an actual backslash or an escape character. Currently, if you want to use a backslash, you must input it as \\ by preceding a \ to indicate that you want the backslash itself, not an escape character.

Solution

Therefore, if the path to the file you want to read is

"C:\Users\rmsms\OneDrive\바탕 화면\example.csv"

Then, to avoid escape characters, change \ to \\ as follows.

"C:\\Users\\rmsms\\OneDrive\\바탕 화면\\example.csv"

Then, you can confirm that it reads correctly as shown above.

Why not \ but /

Meanwhile, while searching foreign sites, you may also see suggestions to change the \ in

"C:\Users\rmsms\OneDrive\바탕 화면\example.csv"

to /.

"C:/Users/rmsms/OneDrive/바탕 화면/example.csv"

Initially, the absurdity of changing from backslash to slash might send shivers down your spine, but in fact, as with most programming languages, it happens because paths are also segregated with slashes to match the Linux environment. It’s not that R is strange, but rather, most languages allow entering paths with slashes, so don’t feel too unfairly treated.

In fact, if you change to slash and read, you can confirm that the data is read without problems.