I have a same problem. If you have google chrome you can do this for widevine.

ll /opt/google/chrome/WidevineCdm/
ll /opt/google/chrome/WidevineCdm/_platform_specific/
ll /opt/google/chrome/WidevineCdm/_platform_specific/linux_x64/

in this path if you have "libwidevinecdm.so" you have to copy path "widevine_config.json" this file.
your file like this:

cat /usr/lib/x86_64-linux-gnu/opera/resources/widevine_config.json
[
   {
      "preload" : "/opt/google/chrome/libwidevinecdm.so"
   },
   {
      "preload" : "/opt/google/chrome-beta/libwidevinecdm.so"
   },
   {
      "preload" : "/opt/google/chrome-unstable/libwidevinecdm.so"
   }
]

first copy "libwidevinecdm.so" /opt/google/chrome
sudo cp /opt/google/chrome/WidevineCdm/_platform_specific/linux_x64/libwidevinecdm.so /opt/google/chrome

then add to this file path widevine_config.json.

sudo nano /usr/lib/x86_64-linux-gnu/opera/resources/widevine_config.json
add this line:

  "plugin" : "/opt/google/chrome/libwidevinecdmadapter.so"

then file like this:
[
{
"preload" : "/opt/google/chrome/libwidevinecdm.so",
"plugin" : "/opt/google/chrome/libwidevinecdmadapter.so"
},
{
"preload" : "/opt/google/chrome-beta/libwidevinecdm.so"
},
{
"preload" : "/opt/google/chrome-unstable/libwidevinecdm.so"
}
]

don't forget the "," :).
hope it helps.

I have a same problem. If you have google chrome you can do this for widevine.

ll /opt/google/chrome/WidevineCdm/
ll /opt/google/chrome/WidevineCdm/_platform_specific/
ll /opt/google/chrome/WidevineCdm/_platform_specific/linux_x64/

in this path if you have "libwidevinecdm.so" you have to copy path "widevine_config.json" this file.
your file like this:

cat /usr/lib/x86_64-linux-gnu/opera/resources/widevine_config.json
[
   {
      "preload" : "/opt/google/chrome/libwidevinecdm.so"
   },
   {
      "preload" : "/opt/google/chrome-beta/libwidevinecdm.so"
   },
   {
      "preload" : "/opt/google/chrome-unstable/libwidevinecdm.so"
   }
]

first copy "libwidevinecdm.so" /opt/google/chrome
sudo cp /opt/google/chrome/WidevineCdm/_platform_specific/linux_x64/libwidevinecdm.so /opt/google/chrome

then add to this file path widevine_config.json.

sudo nano /usr/lib/x86_64-linux-gnu/opera/resources/widevine_config.json
add this line:

  "plugin" : "/opt/google/chrome/libwidevinecdmadapter.so"

then file like this:
[
{
"preload" : "/opt/google/chrome/libwidevinecdm.so",
"plugin" : "/opt/google/chrome/libwidevinecdmadapter.so"
},
{
"preload" : "/opt/google/chrome-beta/libwidevinecdm.so"
},
{
"preload" : "/opt/google/chrome-unstable/libwidevinecdm.so"
}
]

don't forget the "," :).
hope it helps.

I have a same problem. If you have google chrome you can do this for widevine.

ll /opt/google/chrome/WidevineCdm/
ll /opt/google/chrome/WidevineCdm/_platform_specific/
ll /opt/google/chrome/WidevineCdm/_platform_specific/linux_x64/

in this path if you have "libwidevinecdm.so" you have to copy path "widevine_config.json" this file.
your file like this:

cat /usr/lib/x86_64-linux-gnu/opera/resources/widevine_config.json
[
   {
      "preload" : "/opt/google/chrome/libwidevinecdm.so"
   },
   {
      "preload" : "/opt/google/chrome-beta/libwidevinecdm.so"
   },
   {
      "preload" : "/opt/google/chrome-unstable/libwidevinecdm.so"
   }
]

first copy "libwidevinecdm.so" /opt/google/chrome
sudo cp /opt/google/chrome/WidevineCdm/_platform_specific/linux_x64/libwidevinecdm.so /opt/google/chrome

then add to this file path widevine_config.json.

sudo nano /usr/lib/x86_64-linux-gnu/opera/resources/widevine_config.json
add this line:

  "plugin" : "/opt/google/chrome/libwidevinecdmadapter.so"

then file like this:
[
{
"preload" : "/opt/google/chrome/libwidevinecdm.so",
"plugin" : "/opt/google/chrome/libwidevinecdmadapter.so"
},
{
"preload" : "/opt/google/chrome-beta/libwidevinecdm.so"
},
{
"preload" : "/opt/google/chrome-unstable/libwidevinecdm.so"
}
]

don't forget the "," :).
hope it helps.