1. Go to http://archive.ubuntu.com/ubuntu/pool/main/o/openssl
2. find the exact version of libssl for example libssl1.1.1
3. wget http://archive.ubuntu.com/ubuntu/pool/main/o/openssl/libssl1.1_1.1.1-1ubuntu2.1\~18.04.20_amd64.deb
4. Then install
5. sudo dpkg -i libssl1.1_1.1.1-1ubuntu2.1~18.04.20_amd64.deb

Although I think the advice given by Artur is good. I managed to resolve this for a legacy app (specifically easytether-usb) by grabbing libcrypto.so.1.1 from the 1.1 install as referenced by @Nishant in his answer. I installed that in user space under my home directory and created a sym link to it in /lib/libcrypto.so.1.1:

sudo ln -s ~/openssl/lib/libcrypto.so.1.1 /lib/libcrypto.so.1.1

You can normally add ~/openss/lib to the LD_LIBRARY_PATH for the specific application in question, but in my case the leacy app didn't properly look in $LD_LIBRARY_PATH, so I had to find out where it was looking for libcrypto.so.1.1, I did that with the following:

sudo strace -e trace=open,openat,close,read,write,connect,accept easytether-usb

That showed me a dozen or so attempts to find the file libcrypto.so.1.1 in various locations, which is why I knew to add the sym link to /lib/ above.

After that the legacy app fired up and worked like normal. Other uses cases will likely need other shared libraries. the strace command above should help determine what's needed.

I was facing a libssl1.1 issue when trying to install mongo-db in Pop!_OS 22.04 LTS (or Ubuntu 22.04 LTS).

As @stephen-kitt mentioned libssl1.x is an obsolete package. So you need to manually install the required package.

1. Go to this page
2. Find the exact version of libssl for example libssl1.1.1
3. wget http://archive.ubuntu.com/ubuntu/pool/main/o/openssl/libssl1.1_1.1.1-1ubuntu2.1~18.04.20_amd64.deb (use your version url respectively)
4. Then install with sudo dpkg -i libssl1.1_1.1.1-1ubuntu2.1~18.04.20_amd64.deb

Hope this helps others who are trying to do the same.

The issue is referenced on Github, all credit goes to @feisalramar.

FWIW, I ran into this same problem and it turned out to be an issue with the version of wkhtmltopdf I was trying to install. I have an Ubuntu 12.04.5 64-bit system and was trying to install a 32-bit version of the package. Looks like you have the 32-bit version there as well; should it be amd64 instead of i386? All package downloads here: http://wkhtmltopdf.org/downloads.html.

Hope this helps.

I've encountered this issue with 22.04 LTS, ended up writing the following script for my systems to have it installed, as one of the tools I use to setup the system requires it.

Hope others find this useful.

# Find the most recent 1.1 libssl package in the ubuntu archives
BASE_URL='http://archive.ubuntu.com/ubuntu/pool/main/o/openssl'
FILE="$( # The get parameters in the URL sort the results by descending chronological order
    curl -s "${BASE_URL}/?C=M;O=D" $(\
        # Make sure all tags are on separate lines - makes grep-work later easier \
        ) | tr '>' '>\n' $(\
        # extract all the unique links on the page \
        ) | grep 'href' | sed 's/^.*href="\([^"]*\)".*$/\1/p' | awk '!a[$0]++' $(\
        # pick the most relevant items on the list (libssl 1.1 for amd64 arch) \
        ) | grep "libssl" | grep "1.1_" | grep "amd64.deb" $(\
        # choose only the last one \
        ) | tail -1 )"
# Grab the file and if download was successful, install it with sudo
wget "${URL_BASE}/${FILE}" && sudo dpkg -i "./${FILE}"