I have Fiddler 1.6.0 on MacOS Big Sur 11.2.3. Fiddler will launch, however, I see zero traffic being captured and traffic to the internet is blocked/times out waiting on the proxy to respond.
I went into the system Network settings, and indeed the system proxy is setup for localhost and the Fiddler port. However, browsers such as Edge just timeout when accessing the web.
I do NOT have any VPNs active. If I clear the system proxy settings at the MacOS level, then internet traffic resumes.
I did successfully use an older version of FE late last year and it worked fine on Catalina.
That is definitely strange. It seems like there's a problem with the proxy configuration, which could be caused by various reasons (for example leaked process or incorrect setup of the proxy settings in the network adapter). In order to try to determine which one causes it, can you please try the steps below and share the results:
Step 3 in the first section simply hangs. I don't get a response, but I do see a single line in the capture tab (but no data). If I untick the proxy settings at the MacOS level, then the composer query will return data. The curl command just hangs when I try to run it with system proxy settings turned on.
I then changed the proxy port in FE to 8686. For a split second I got 161 entries in the Capture window, but all are stuck at CONNECT. I should also mention upon startup of FE, that I see a spinning circle outline for the longest time. This is far different behavior from the late 2020 FE, where it just worked out of the box on Catalina.
In the netcore.log I see a TON of:
Stream Error: Server timeout elapsed without receiving a message from the server.. Keep the stream in the active ones as it could be
Stream Error: Invocation canceled due to the underlying connection being closed.. Keep the stream in the active ones as it could be reconnected in the connection state handlers.
Thank you for the provided additional information. Based on it, I think there might be a leaked process from old Fiddler Everywhere instance. Can you try the steps:
1. Stop Fiddler Everywhere.
2. Open Terminal and execute the command: ps -ef | grep Fiddler.WebUi | grep -v grep
3. If you see any result, it means there's a process running, while it shouldn't be and you should kill it (you can do this by executing kill -9 <pid>, where <pid> is the value of this second column in the returned result). If there are no results, all the processes are already finished their work and there are no leaked ones.
Regarding the multiple CONNECTs, can you please open the Settings in your Fiddler Everywhere applicaiton and ensure the Capture HTTPs traffic checkbox is checked. You may try using the Reset root certificate button in the Advanced section to ensure the root certificate is correctly trusted. Without this, you will not be able to see HTTPS traffic in the app.
Can you please check those and see if they help?
Things are getting worse. I did do the ps command, and yes there was a straggler process running which I killed. Now, when I launch FE it's stuck on "Please wait" with the green paper airplane. After a long time (20-30 minutes) it says I can't login due to a backend error. I de-installed FE and tried again, and the same login issue keeps happening.
This is definitely not expected. Can you try opening the following URL in your browser: https://api.getfiddler.com/index.html
As a result you should see something similar to the attached image. If you do not see the same thing, it probably means you do not have access to this URL.
Additionally, can you send us all the application logs (all electron.log and netcore.log files)?
Looking forward to hearing from you.