The error 'unable to locate package redis-server' typically occurs when the system can't find the Redis package during installation. It could be due to several reasons, such as outdated package lists, missing repositories, or incorrect package names.
One of the common causes of this error is that the package list on the system might be outdated, which means that the system isn't aware of the latest available packages, including Redis. Additionally, there may also be a possibility that the repository required for installing Redis is missing from the system. Lastly, the package name for Redis might not be correct, resulting in the system being unable to locate it.
To resolve the 'unable to locate package redis-server' error, you can take several steps. Firstly, update the package lists by running the command 'sudo apt-get update,' which will refresh the package lists and make the system aware of the latest available packages.
If that doesn't work, check if the repository required for Redis installation is added to the system. You can add the necessary repository by running the command 'sudo add-apt-repository ppa:redislabs/redis' and then updating the package list again using the previous command.
Lastly, if you're still unable to locate the Redis package, ensure that you've entered the correct package name. You can confirm the correct package name by visiting the Redis website or running a quick search. If the issue persists, try restarting your system and trying the above steps again.