While developing with create-react-app, my browser enters debugger mode on warnings:
It breaks on the source code of react-dev-tools:
// --- Welcome to debugging with React DevTools ---
// This debugger statement means that you've enabled the "break on warnings" feature.
// Use the browser's Call Stack panel to step out of this override function-
// to where the original warning or error was logged.
How can I deactivate this behavior?
Go to Chrome Devtools → in the Chrome console, go to Component → Click on Settings → unset Break on Warning. Do the same in Profiler → Settings → unset Break on warning.
#cadoman pointed check and then uncheck to make work for sure.
P.S: Image from https://github.com/facebook/react/issues/19308#issuecomment-656669792
Based on pull request DevTools: Make break-on-warn off by default #19309 it seems it's a bug.
The Break On Warnings box was unchecked for me and it still would break. Removing and readding the extension to force an update fixed it for me.
I don't know of another way to force Chrome to update an extension outside of its regular schedule.
Go to your ReactDev tools in the tab Debugging and disable "Break on Warning".
I think this new behavior started today with this new PR: https://github.com/facebook/react/pull/19048
Chrome has a "BlackBox script" feature which is useful in this case.
Go to Chrome Developer tools -> source tab
Select "react_developer_tools.js" from the left pane
Right-click file and select "Blackbox script"
It's a known issue. A workaround is posted on GitHub: Bug: Unexpected debugger statement in DevTools (solved) #19308
The issue is due to a recent release. A Workaround proposed by the React team is:
Go to Chrome Developer Tools
Click on the Components Tab (React Developer Tools Extension)
Click on the Settings icon (located next to the component search box)
Once modal opens select the Debugging tab
Finally, double click on the Break on Warnings checkbox (check and unchecked)
Make sure at last the Break on Warnings checkbox is unchecked.
Reference: Issue link
Related
Now I can see about VM line in my chrome developer tools like this.
There are some solution that I found,
such as make gray 'pause button'
however, it was already gray in my developer-tool
and it was also not worked for me.
How can I get rid of that VM messages in my console?
Thanks for read my problem.
With the right mouse click on a VM:xxx link select "Reveal in Sources panel", and study the code that causes those console messages.
In my case, I found there this line - original Method(...format WithStyles(args, 'color: ${color}'));, and other lines there revealed that it was referring to React Devtools Extention. So in its "Components" console tab => Settings gear icon => Debugging tab => I checked on the "Hide logs during second render in strict mode" option.
It helped me, but it can be some other extension in your case. Study the source code of a message first.
Open Chrome console, than select All Levels (it may appear like Default, if so, click it.) See in the list if Info is checked. If it is checked, close it. It helped me to get rid of it, hope it will help you to get rid of [VM] line in Chrome console too.
Check the image below:
My React app has started running this line out of the blue and interrupting my development. The file is React_devtools_backend.js
debugger;t.apply(void 0,o)};n.__REACT_DEVTOOLS_ORIGINAL_METHOD__=t,// $FlowFixMe property error|warn is not writable.
Any ideas why and how to fix this?
It is a bug in React Dev Tools (version: 4.8.0). You can see the issue here. If you use Firefox and update the extension, probably it is going to be fixed. If you are using Chrome, the update is still pending but you can find a temporary solution in the issue link.
Temporary solution:
You should also be able to go to Components tab, press Settings gear,
add checkbox to Break on Warning, then do this again, and remove the
checkbox as a temporary workaround.
This issue has a momentarily quick fix if you're on Chrome (react-devtools#4.8.0):
Open React-DevTools > Components.
In the upper right corner, click the Settings gear icon.
Go to the Debugging tab.
Check Break on Warnings.
Uncheck Break on Warnings.
Finally, reload the page.
I am trying to get my react extension working for local development, but "Components" and "Profiler" is missing in the Chrome developer tools. This only happens for local development, any other production code is displaying the two tabs in the developer tools as expected. I was wondering if this can be resolved somehow? I triple checked if the tabs are hidden on that occasion, and they are not. As said, this only happens for development version. When I click on the extension, I get the following message:
This page is using the development build of React. 🚧
Note that the development build is not suitable for production.
Make sure to use the production build before deployment.
Open the developer tools, and "Components" and "Profiler" tabs will appear to the right.
Based on this information I should have the tabs displayed.
When I go to a production app and click on the React extension, I can see the following displayed:
This page is using the production build of React. ✅
Open the developer tools, and "Components" and "Profiler" tabs will appear to the right.
And I also see those two tabs without a problem.
Any idea why this would happen? I searched for a solution, but did not encounter one. The only thing I found was someone mentioning you need to set the environment variable REACT_APP_ENV. I tried to set this value in the .env file where I defined REACT_APP_ENV='dev' as well as REACT_APP_ENV='development'. It did not resolve the issue, even with application and browser restart.
This happened to me as well. Looks like a bug in Chromium, but a temp solution is:
Change the chrome DevTools theme, only once it is required.
Now open devtools, you find the extension tab in DevTools.
You can again change the theme whatever you want to keep and this will fix your problem.
Check this out:
https://github.com/facebook/react/issues/19002#issuecomment-637462179
Was having the same issue, the Components and Profiler tabs weren't showing up, so I tried changing the theme as suggested by BobTheBuilder, that didn't work, so tried setting the debug levels to Default + Verbose (in addition to the others) in the console and they finally showed up.
The steps that helped me:
Remove React Developer Tools extension
Install React Developer Tools extension
Open a brand new tab containing react app
Open Dev Tools
React Developer Tools should be available
I had the same issue where Components and Profiler tabs were not showing. What worked for me was to open up the DevTools settings and to click the 'Restore defaults and reload' button (under the 'Sync' heading).
The steps that worked for me
Open chrome extensions
Disable the react dev tools extension
Enable the react dev tools extension
Enable Developer mode
Refresh target page
Where steps 1 and 2 are the little slide control at the bottom right of the extension in the extension manager.
Step 4 is the slider in the top right above all the extensions in the manager.
I was executing webextension on Firefox for testing with about:debugging menu.
Then tests are done, I want to stop it.
I am looking for a way to stop without shutdown browser, but I can't find a way to stop it out.
Is there way for do it without shutdown browser?
Just like a normal add-on, you can disable or remove a temporary WebExtension that was loaded from about:debuging from about:addons (Ctrl-Shift-A, or Cmd-Shift-A on OSX) . If you "Remove" it, and then refresh about:debugging you will see that it is gone from that list.
If you do not refresh about:debugging after disabling or removing it, it will remain in the list that is displayed. This can be convenient if you are testing behavior when the add-on is installed or removed.
The following gif shows loading and removing an add-on named "aaaaaaaaaaaaaaaaaa - demo add-on":
If you do not refresh about:addons after removing an add-on, the add-on will remain in the "uninstalling" state. From that state you can "Undo" the removal/uninstall. This is displayed in about:addons with the "Undo" link. The fact that an extension is in this state is not available to WebExtension add-ons, but can be seen from other Firefox add-ons using the Add-on Manager API. The Add-on Manager API is not compatible with WebExtensions. If you want to take a look at a Firefox Add-on SDK based add-on that shows these states, you can see my answer to another question.
I am working on a site: greatlakesecho.org When I try to edit a post, the content just disappears from the visual editor. I am running the latest version of Word Press but this happened on the previous version as well. I am using the Project Largo theme with the site.
The site was recently migrated from to a new host and has gone an overhaul into a responsive design. This first started happening when I changed the character encoding to remove odd symbols from the posts. I was successful in that by changing it to utf16. At this point only older posts that were created before the migration would disappear when I clicked edit. I have since updated to the latest version of Word Press and it happens to every post.
I've already made sure the wp-config has the correct encoding.
It happens with all themes.
Tried deactivating all plugins.
I also see this when enabling debuggin:
WordPress database error: [Table 'greatlak_wp776.wp_itsec_lockouts' doesn't exist]
SELECT lockout_host FROM wp_itsec_lockouts WHERE lockout_active=1 AND lockout_expire_gmt > '2014-04-22 19:52:36' AND lockout_host='35.9.132.246';
WordPress database error: [Table 'greatlak_wp776.wp_itsec_lockouts' doesn't exist]
SELECT lockout_user FROM wp_itsec_lockouts WHERE lockout_active=1 AND lockout_expire_gmt > '2014-04-22 19:52:36' AND lockout_user=93;
edit: Extra Info
Wordpress has this documented on their documentation. It can be found here, of course you will be converting to utf16 instead of utf8. http://codex.wordpress.org/Converting_Database_Character_Sets
Check your wp-config file's encoding, make sure it's set to utf-16
Activate a new theme, see if that still happens. If so, it was a theme issue.
Deactivate all plugins, see if it still happens. If so, reactivate 1 by 1 and see when it happens again.
Also, check your browsers console for any errors
I had to remove the Navis Media Credit plugin manually. I searched through the plugins folder using WinSCP and apparently when I was removing all the plugins using the WordPress admin panel, this one wasn't actually getting removed. This plugin was conflicting with the theme I am using and I learned this by deleting all the plugins and using one of the default WP themes.
It may be a Chrome Extension. Here is what I experienced...
In Chrome - a Wordpress site loads the Add New Post screen which appears to get overwritten - this happens after typing a few characters (not immediately) in the title or body. Updated theme, removed plugins, no change. At one stage noticed a bug in html2canvas.js but now cannot reproduce.
Tested in Firefox, works fine.
Traced to a Chrome Extension - Screen Shader - F.lux for Chrome 1.7.720 - one that removes BLUE from Chrome display (for night work). It probably does use use html2canvas. When it is deactivated, Chrome again behaves normally. Tried with another plugin "Blue Light Filter Guard" - not as well featured - but it does not trigger the bug.
May not be the same as your problem, but try in Firefox and check your Chrome Extensions.