Hello, I have the same problem. “Error Saving Item” and I cannot save any new words! I tried refreshing everything and signing in and out of the extension. New words don’t appear on the “Language Reactor”.
I paid the premium subscription to be able to use this for studying a new language. I love the tool but this error is making a problem to my studies. Please fix it as soon as possible 
Learning German (via English) on Netflix
I have also been having this “error saving item” problem for a couple of days on every video I watch. I reinstalled the extension and it worked for a few minutes and then started getting the error again. I also pay for the premium subscription. So would love for it to be fixed ASAP!
This is my favorite language tool by far!
I have the same error too. And this situation has already emerged three days.
This started happening for me just now
I am having the same problem. restarted computer, browser, uninstalled and reinstalled the extension. Nothing has worked. Since I am paying for the pro version, I expect this to be fixed asap.
Language Reactor Error: Failed to retrieve linguistic data: NETWORK_ERROR Lang: ja, tt_key: SUBS_ja_1_d1b902d195070d54a23f6b73293578a9
This practically renders the extension useless, as no features whatsoever can be used (apart from navigating to the previous/next subtitles with the keys).
Update for my . “Error Saving Item” problem:
I think it is a problem with his server storage getting full. It used to happen to me but not anymore. I think the old accounts get deleted and it makes room for you to save new words. This is just my guess.
There is nothing from your side that you can do to fix it. Just wait and it will work eventually.
For me it started working again 1-2 days after. Then i had the same problem 2 weeks later, but it lasted only for 1 day and it started working again. I didn’t do anything specific to fix it. Just the normal troubleshooting but it didn’t work. You just have to wait and it will work eventually. It is a problem on their server and not your computer.
ok, thanks. let’s see then.
Having the same error from today.
I don’t think it’s because you’re in Russia. It’s happening to me as well
I’m also having the same problem. Just started using LR yesterday and was already planning on subscribing but this isn’t really a good start. 
This happened to me a couple of times since I started using it and it usually goes away on it’s own. I subscribed for it to keep track of which words I know and it’s been phenomenal. Can’t go back to not having it now.
I just installed and got the 12 day pro trial. I’m on day 3 and already it’s bugged and I feel like I’m blind with all my saved words gone. This isn’t really helping persuade me to stick with the Pro version.
Yes it’s really sad to see all that good work tainted by a disk capacity issue. I hope you find a stable solution!
Hi. I am still experiencing this issue too. Has it been resolved?
I just got this, subscribed yesterday but this is not quite a good start.
Hi all! Currently receiving a similar error on both YouTube and Netflix. Hopefully this can be fixed promptly
Language Reactor Error: Failed to retrieve linguistic data: NETWORK_ERROR Lang: de, tt_key: SUBS_de_1_f5f182a599edcd595b97bf0607ea97e5
same issue here on YouTube.
Language Reactor Error: Failed to retrieve linguistic data: NETWORK_ERROR Lang: en, tt_key: SUBS_en_1_8c84638d902d17d07e7f82b0607ec1bc
please tell us how to fix it?
Language Reactor Error: Failed to retrieve linguistic data: NETWORK_ERROR Lang: ja, tt_key: SUBS_ja_1_51a88103c85af1d1ce0658473a1e2bef
正常のネットワーク（ネットサーフィン）はできるのに、この表示がでます。対応方法をしりたいです。せっかく登録した単語たちが…
I get it, that stuff happens. It happens with LR more than I like. Sometimes it’s a small thing, other times, it’s basically useless, as it is now for most. A program is only as good as when it is working. I have a study plan which includes using LR. It’s been dysfunctional a couple of days for me. My subscription comes due in two week and unlike some, I simply can’t afford to pay for things which do not fulfill the need. I am over 70 and I try to use my time wisely which includes how I use my study time. Now, the point of this rant is that, unless I am missing something, I do not see any notification or response from the developers. Keeping me guessing just pisses me off. I would really like to see something telling us the problem, what they are doing about it and approximately how long it could take. That way, I can use other tools to study while this gets fixed. This is not the first time it’s been unusable. That’s my say.
In this day and age where we have so many alternatives’ consistency is key. Really disappointed in LR.