: Use a hex editor or a file signature tool to see the actual first few bytes of the file to determine its true format.
: Real RAR archives use the following headers: RAR 5.0+ : 52 61 72 21 1A 07 01 00 RAR 1.5 to 4.0 : 52 61 72 21 1A 07 00 00 X 2 6 1 1 C E 00 X rar
: If the file is legitimate but corrupted, tools like Keka or UnRarX may be able to force an extraction or provide a more detailed error report. : Use a hex editor or a file