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Checking for errors in browsers

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Tutorial written by AshleyOriginally published on 3rd, December 2011 - 4 revisions

By default browsers don't display any error messages when things go wrong. This is so your experience browsing the web is smooth and not interrupted with lots of annoying error messages. However, if something goes wrong with your Construct 2 game, you won't see any error message at first. This can make it difficult to work out what has gone wrong.

To see error messages, you first have to open the Developer Tools or Error console in the browser. These error messages are very useful to add to bug reports! It's also a good idea to check for errors after publishing your game to ensure it is working properly. If you have a problem with a Construct 2 game, try these shortcuts to look for error messages:

Internet Explorer: Press F12 to open Developer Tools. Note that Internet Explorer annoyingly won't show any errors from before you pressed F12, so it's likely you'll have to press F12 then refresh the page to see the error message. Other browsers are better and show error messages from before you opened the error console, so you don't need to refresh the page.
Google Chrome: Press Ctrl + Shift + J to open Developer Tools. There should be an error log at the bottom of the pane that opens - if not, click the Console tab.
Firefox: Press Ctrl + Shift + J to open the error console. Note you may want to press Clear and refresh the page otherwise you might see error messages from other websites. Press Ctrl + Shift + K to open the advanced log which contains more detailed information.
Opera: Press Ctrl + Shift + O to open the error console.
Safari: Press Ctrl + Alt + C to open the error console. On iPhone or iPad you can enable Debug mode under Safari - Developer or Advanced in Settings. This will show errors in a bar at the top of the screen which you can tap for more information.

Common errors

Blank or "grey" screen on preview
Something has gone wrong - use the shortcuts above to find any error message. You might want to post a bug report including the error message.

Game freezes half way through
Something has gone wrong - use the shortcuts above to find any error message. You might want to post a bug report including the error message.

Game works in preview but not after exporting
This is usually caused by broken third-party plugins and behaviors which do not work with the minifier. The error message will probably include random characters like is undefined. Try removing third party plugins or behaviors. You should report the problem to the plugin or behavior developer, since Scirra cannot fix it. If you are not using any third party plugins or behaviors at all, you should post a bug report.

On my server I see the error "Invalid manifest mime type (text/plain)"
Every time I play the game on my server it re-loads from scratch and is wasting my bandwidth
Your server is set up wrong and this is breaking the offline support. See Offline games in Construct 2. You need to add the MIME type text/cache-manifest for the file extension .appcache on your server.

No audio plays or My sound files come up as 404 not found
Make sure you've set the following MIME types on your server:
.ogg files: audio/ogg
.m4a files: audio/mp4

Some other files come up as 404 not found
Did you upload the entire project and all its files and folders? You might have forgot to upload everything.

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zenox98 62.9k rep

Very simple and easy instructions. Nice :)

Saturday, December 03, 2011 at 3:13:31 PM
diascarlosryal 3,949 rep

Great! Thanks for another very useful tutorial!

Saturday, December 03, 2011 at 5:17:03 PM
guicole 3,600 rep

Great tutorial!

But I have a question, maybe it's not the right place... sorry if it's not.

I have a error concerning Ajax and Https
I want to have a secure connection (facebook game) so everything has to be in https
but I have a error concerning an Ajax request :

"The page at https://[...]/christmasrush/ ran insecure content from

Is there a way to change the Url of the Ajax in Https ?
If I change in the exported files, I will have to change it everytime ?

Thx for the answer, you're great!

Saturday, December 03, 2011 at 6:48:22 PM
Ashley 202.2k rep

@guicole, find the reference to http://ajax.googleapis... in the HTML source code and change the http to https.

Saturday, December 03, 2011 at 6:50:54 PM
orangemicro 3,429 rep

Awesome! This is definitely good to know. F12 also works for Google Chrome, which I find easier.

Friday, July 05, 2013 at 2:47:01 PM

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