This problem is shown after i installed the latest update of FE.

Session captured list is normal, you can set filter/sort or scroll, but the panel is frozen and keep circle-ing. Can not change tabs(Overview/Inspectors/Rules).

Actually, it looks like only frozed UI, the click event still response.(Like i click My Session-facebook, UI doesn't shows because forzed, but after a reboot of FiddlerEverywhere you will find facebook tab is already open beside Composer.)

I can't provide a valid session file for you to debug, because if i confirm a session will cause the forzen, i will not be able to select format or location or click done, just like the screenshot shows. 

But i will provide a similar one. You can try to view those json session, it will frozen after about 3 sessions.

Hey everyone,

We've just released Fiddler Everywhere v3.0.1 with a fix for this issue. You can check all the release notes here.
To get the latest update, just start the product and it will download it automatically. If it does not happen, you can use th Help -> Check for updates option.

Thanks again for all the provided information!

Regards,
Rosen Vladimirov

Hey everyone,

Thanks a lot for all the information you've sent. We've identified the issue and we've implemented a fix. Our QAs are currently testing it and we'll release it as part of our incoming 3.0.1 version in the next days.

Details about the issue:
With 3.0 release we've decided to implement a change in the automatic selection of the inspectors. We've analyzed the experience and multiple use-cases and decided that for single selection in the session list, we'll not change the currently selected inspector. However, we wanted to have an easy way to show the most appropriate inspector, so we've used a well known action - double-click. When such action is used, the most appropriate inspector will be selected.
When we implemented the change, we've tested it with multiple different scenarios and we did not notice any issues.
Later, with the implementation of another feature, we had applied changes in the internal component used for visualization of the form-data. At this point, we had introduced an issue in the component, but due to the way it is used, it did not occur during our manual and automated testing. 
The main problem occurs when form-data Body inspector is selected and then another session, which is not form-data is selected while the Body inspector is still focused. The issue is not visible immediately, but if you select another session with form-data, the loaders in request/response show that there's some big trouble.

Workaround
There are at least two workarounds here:
- Whenever you inspect form-data, before switching to another session (no matter if you use single or double click), switch to another inspector, that's not the Body one, for example Headers
- Inspect form-data only in Raw tab, this way the Body will not be selected when switching between sessions and the issue will not occur.

Prevention of such failures in the future

In order to ensure we'll not hit such issue in the future, we've planned improvements in our process for defining acceptance criteria and for the automated tests. Of course, we all know there's no bug free software, so your help on such issues is greatly appreciated. 

And finally, thanks again for all the details you've all sent us. It was a great help and it allowed us to identify the issue quickly. Please accept our apology for the caused inconvenience. We’ll write back when we release the 3.0.1 version.

Regards,
Rosen Vladimirov

Hey,
I am having the same problem, but I am on windows. It happens for me when I click on a POST request which has a form body after clicking on a similar request, regardless whether its a saved session or in Live Traffic.
I was able to take a look in the log files and I found this error in electron.log with the exact timestamp when the UI crashed:

[2021-12-01 19:06:47:066] [info] [WebUI] crit: Fiddler.WebUi.Controllers.AngularLoggingController[0]

      Cannot read properties of undefined (reading 'length')

[2021-12-01 19:06:47:083] [info] [WebUI] crit: Fiddler.WebUi.Controllers.AngularLoggingController[0]

      Cannot read properties of undefined (reading 'length')

Hope this helps to fix it!

Hi I am also having the same problem as well, fiddler is able to live capture data traffic. however when i click on one of the host, the request body under inspectors keep on loading  and buffering non stop. I am unable to extract the key value from the website

Hey,

Thank you very much for the provided information. We are still investigating the logs, looks like there might be some specific problem with requests having form-data bodies. 
We continue our investigation, but it will be a great help in case you can export a .saz file with a session which leads to the unexpected hang. Just righ-click on it and select Export -> Selected sessions. Then you can send the generated file to us for investigation.

Thanks again for your help!

Regards,
Rosen Vladimirov

And another detail: If you signle click a session, switch to request body, switch back to other tabs, then single click other session, fiddler everywhere will not froze.

Yet another detail i notice:Event if i only use single click to view the data, it will still forze after some special action, Here is the list:

Single click a session, switch to request body(only this one, other request tab and all response tab are normal), signle click another session, forze

Addition to the problem:

I've found that single click is doing totally fine, not causing the forzen, but double click will.

Detail: Double click a session, then double click another session, frozen.

I suppose that it may be the new feature of 3.0 realease as screenshot

@Rosen Vladimirov

Here is my log files zip, I don't know how to @ in this forum but maybe you will recieve a notification email

I've been keep using fiddler everywhere since i post the topic, you may need to search for timestamps or other info for error detail

Hey,

The behavior is definitely not expected. Can you please share with us the Application logs - you can access them through the top-level menus Help -> Open Application Logs Folder. If that's also frozen, the actual directory is '~/Library/Application\ Support/Fiddler\ Everywhere/Logs' - we'll need all the files from there for investigation.
If you do not want to share the files in the public forum, you can send us a ticket by using the Help -> Contact Support option of the application. 
> NOTE: You'll need to use the email with which you've started your trial in the application for the "Contact Support" option

Looking forward to hearing from you!

Regards,
Rosen Vladimirov