Hello

Can you provide a sample apk of the app? Also, please provide logcat & bugreport for your issue.

This is affecting Chrome as well. When attempting to debug a page on a device using  chrome://inspect the print pretty button is failing to do anything, as described. In the dev tools on a page open on the desktop the print pretty works fine.

Tried with Linux 60.0.3112.113 (Official Build) (64-bit), and Mac 63.0.3212.0 (Official Build) canary (64-bit).

Device was Android 7.1.1; Pixel 63.0.3201.0 (Official Build) canary (32-bit)

This makes debugging issues with sites using features currently only supported on mobile (e.g., VR) difficult. Do you have an idea of what might be wrong or how to work around this?

More specific repro steps:

- use Chrome Canary (63.0.3214.0) on Android, Linux 60.0.3112.113 (Official Build) (64-bit) on desktop
- Open a web page with minified source, I used https://bugs.chromium.org/p/chromium/issues/detail?id=715452

- in chrome://inspect/?tracing#devices, click "inspect" for this tab

- click on "Sources" tab in inspector, see minified source

- click on "{}" pretty-print icon

=> nothing happens

If I inspect the inspect page by pressing Shift-Ctrl-J in the inspector consoles, I see a "Failed to load resource: net::ERR_FAILED" message:

[Deprecation] Use of the Application Cache is deprecated on insecure origins. Support will be removed in the future. You should consider switching your application to a secure origin, such as HTTPS. See https://goo.gl/rStTGz for more details.
inspector.html:1 Document was loaded from Application Cache with manifest chrome-devtools://devtools/remote/serve_rev/@21dea15ba6117af0b06bd89c6dd6f427a016423d/21dea15ba6117af0b06bd89c6dd6f427a016423d.manifest
inspector.html:1 Application Cache Checking event
[Deprecation] /deep/ combinator is no longer supported in CSS dynamic profile. It is now effectively no-op, acting as if it were a descendant combinator. You should consider to remove it. See https://www.chromestatus.com/features/4964279606312960 for more details.
inspector.html:1 Application Cache NoUpdate event
inspector.js:8272 Main._createAppUI: 28.341064453125ms
inspector.js:8272 Main._showAppUI: 10.383056640625ms
inspector.js:8272 Main._initializeTarget: 12.56787109375ms
chrome-devtools://devtools/remote/serve_rev/@21dea15ba6117af0b06bd89c6dd6f427a016423d/formatter_worker.js?remoteFrontend=true&dockSide=undocked Failed to load resource: net::ERR_FAILED

Does this help narrow it down?

More specifically, the last line in the log message I posted in comment #7 gets added when I click the pretty-print button, and since it's apparently a loading error for "formatter_worker.js" it seems highly relevant. The earlier lines always appear, I had included them for context.

Joel, could you please take a look at this?

This seems related to application cache. The formatter_worker module is not loading after it is cached. Opening devtools in devtools and clearing the cache causes the formatter to work.

einbinder@, I can't get the workaround to work.

Starting point: I'm on an inspector page with pretty-print not working.

- press Shift-Ctrl-J to inspect inspector

=> new console shows error: Failed to load resource: net::ERR_FAILED for chrome-devtools://devtools/remote/serve_rev/@76cc846b87194b6def876c7697854207ab0948c9/formatter_worker.js?remoteFrontend=true&dockSide=undocked

- go to Network tab of the layer 2 inspector, verify that "Disable cache" is checked, press F5 to reload

- go back to layer 1 inspector, press "{}" again

=> layer 2 inspector console shows: inspector.js:444 GET chrome-devtools://devtools/remote/serve_rev/@76cc846b87194b6def876c7697854207ab0948c9/formatter_worker.js?remoteFrontend=true&dockSide=undocked net::ERR_FAILED

I am having the same problem as klausw@ mentions in #11, with the same behaviour save that my error reads has inspector.js:449 instead of inspector.js:444.
 
Chrome version: 61.0.3163.100 (Official Build) (64-bit)

Any updates on this?  Getting complaints from external developers working on Chromecast apps as well.

Sorry for the long delay. There was a patch to fix this same underlying issue:
https://chromium-review.googlesource.com/c/chromium/tools/chrome-devtools-frontend/+/762143