Example:

r <- archiv(c("https://www.google.com", "NOT a URL", "https://qdr.syr.edu"), method="perma_cc")
[[1]]
[1] "https://www.google.com"                                           
[2] "5RVF-7BCE"                                                        
[3] "2019-03-02T21:31:15.669256Z"                                      
[4] "//perma-archives.org/warc/5RVF-7BCE/https://www.google.com"       
[5] "//perma-archives.org/warc/5RVF-7BCE/id_/file:///5RVF-7BCE/cap.png"
[6] "https://perma.cc/5RVF-7BCE"                                       

[[2]]
[1] "Not a valid URL."  "https://perma.cc/"

[[3]]
[1] "https://qdr.syr.edu"                                              
[2] "TYZ8-H8P5"                                                        
[3] "2019-03-02T21:31:17.061622Z"                                      
[4] "//perma-archives.org/warc/TYZ8-H8P5/https://qdr.syr.edu"          
[5] "//perma-archives.org/warc/TYZ8-H8P5/id_/file:///TYZ8-H8P5/cap.png"
[6] "https://perma.cc/TYZ8-H8P5"                                       

Error in names(x) <- value : 
  'names' attribute [6] must be the same length as the vector [5]

The problem being that the vector for the "Not a URL" line is too short. It needs to be the same length as a successful save