This issue is the same like in Inspector: "No element selected" (No CSS) but since the last update to 77.0b3 (64-Bit)
On the websites I am working on the CSS Panel is empty and shows no Stylesheets at all. Some websites work, some not.
I tried also in Save Mode, Reset all settings etc. but that did not help.
@elisasophia hi
Can you try to open the Browser Console and see if there are errors logged there? (Tools > Web Developer > Browser Console).
Do you reproduce the issue on a public website we could use to test? If not, can you share some more info about the kind of websites you are working on (are you using hot reload, specific frameworks or tools etc…)
Thanks
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@jdescottes Thanks!
The Browser Console only shows Warnings, no errors. You can test on “///removed example url///” for example. Can you reproduce it?
Edit: I switched to Firefox 76.0.1 (64-Bit) to be able to continue working and initially it worked there. but now the same bug like in the developer edition…
Thanks for the info!
I can’t reproduce the problem so far.
I have tried to open the inspector both via the “Inspect Element” menu item and using a keyboard shortcut.
If you try to select another element in the inspector’s markup view, do you still see “No element selected”? Don’t hesitate to add screenshots and to share the exact steps you are using to reproduce the bug.
Thanks.
Yes in the beginning the css inspector is completely blank, after browsing on the website and clicking through the elements it always shows “No element selected” and “No CSS-Properties found”
I am working on a Joomla Website Template, having scss compiled into a template.min.css. Last year I had the same issues but I could use the inspector after restarting the browser or opening a new tab. This time it does not help at all.
Thanks for the additional details!
I still can’t reproduce the issue, so I will create a Bug to get more eyes on this.
I filed https://bugzilla.mozilla.org/show_bug.cgi?id=1636660
Did you also try with a clean profile? (https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Multiple_profiles)
If it works with a clean profile, attaching the information from about:support on the faulty profile could help investigating.
A clean profile seems to help - what could be the reason here? Thank you!
Glad it was useful!
Hard to say what the issue could be with the other profile. If you still have access to this other profile, can you go to about:support, use the “Copy raw data to clipboard” and attach the output here?
The issue re-apeared with the clean profile now too…
Then I switched the profile back to another one, and it did not help, today I restarted my browser and it works in all profiles. Maybe switching the profiles did not really help and it was only coincidence …
Now it works everywhere, If it stops working again I can paste the data…
Elisa is not the only one. This problem has appeared randomly for me several times over the last few months. Once it starts claiming there is no element selected, it will continue that way during that session of browser use and perhaps longer - it’s hard to predict what will shake it loose. It might be memory-related, but I’m not sure.
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Same intermittent issue here. The CSS Inspector sometimes works, sometimes reads “No element selected” although an element is selected.
Yes for me also still - the tool usage is very buggy 
I just found this topic as I resumed using Firefox in the Summer and it bugged me that sometimes the Developer Tools wouldn’t show the css for a selected element. After some trial and error I found that it worked in a Private Window, and by working back, I found deleting cookies for the website I was inspecting, I got the css for elements to show again. Hopefully this workaround will help someone who finds the same issue.
Not sure if it’ll help, but I ran into this several times with a Blazor Server app.
When the Blazor Server shuts down, the webpage shows a “reconnecting” overlay with attempts to reconnect to the server up to 8 times and an infinite loading icon. If all attempts fail, it shows an error message. I was working on the CSS so I was shutting down the server, inspecting the overlay and the loading icon, and changing the CSS both in the inspector and in the stylesheet file, and multiple times about halfway through the reconnection attempts Firefox just stopped showing CSS rules and I got “No element selected” instead.
I tried to reproduce it again after finding this thread, but it hasn’t happened again in 3 attempts so I don’t know 