E:malformed entry 1 in list file /etc/apt/sources.list.d/cassandra.sources.list(component)
There is an error in line 1 of the file
etc/apt/sources.list.d/cassandra.sources.list which was added to your system by a user who has
We can't see the contents of that file, thus can't help except to say correct the line, or remove the line/file.
Also note, there maybe more than a single line in that file, and the first error discovered on line 1 caused all subsequent lines to be ignored, thus fixing line 1 may mean subsequent error(s) maybe discovered as they were ignored due to error line line 1..
I'll provide apt - How do I remove a malformed line from my sources.list? - Ask Ubuntu as it maybe helpful (refer to answers).
Welcome @nagarju to the community!