Web servers often serve WASM with incorrect MIME type; better docs/errors needed

[Toad06]

Hello,

I get an error when using a Web build on my site. Here is what is logged in the console in Firefox (Windows):

Loading SWF file images/file.swf
TypeError: Response has unsupported MIME type
Got SWF data
TypeError: Response has unsupported MIME type
Serious error loading Ruffle: TypeError: Response has unsupported MIME type
Serious error occured loading SWF file: TypeError: Response has unsupported MIME type

Chrome (Windows) is a bit more explicit:

TypeError: Failed to execute 'compile' on 'WebAssembly': Incorrect response MIME type. Expected 'application/wasm'.

It turns out the server interpreted the .wasm file as being of type "octet-stream". However, testing the build locally with WampServer has not solved the issue, despite the correct mime type being returned.

There is no issue on iPad (iPadOS 13 - Safari and Chrome), Ruffle runs as expected.

Thanks.

---

UPDATE:

Actually Apache needed an extra line in the .htaccess (even in the local server):

AddType application/wasm wasm

... and clearing browser's cache after this.

[Herschel]

The error happens because WASM files are not served with the proper MIME type of application/wasm on many web servers, and the servers often require configuration to set this.

We should add this somewhere to the docs because it is a common problem, and possibly we could even have the JS detect this when trying to instantitiate the wasm and show a better error in-page.

[Toad06]

Thanks a lot for your answer.

One last thing I would like to report about the Web build is that files that have already been played can look very messy when they are played another time (this may be a known issue).

For example:
http://ruffle-rs.s3-website-us-west-1.amazonaws.com/builds/web-demo/index.html?file=uniwar.swf

• During the intro, the ship is correctly displayed.
• When you get into the hall, the background is not blurry.
• Refresh the page and notice the differences.

This seems related to files caching, as opening the Console > Network > Checking "Disable cache" prevent this issue to happen.

Thanks again!

[Dinnerbone]

I've added some text explaining what this issue is and how to fix it for Apache and NGINX over at the "Using Ruffle" page on the wiki. For other server software we should ask them to post here so we can amend the documentation going forwards.

https://github.com/ruffle-rs/ruffle/wiki/Using-Ruffle
(specific change: https://github.com/ruffle-rs/ruffle/wiki/Using-Ruffle/_compare/fed447678a621485a79a7dc14c27898e59dc4f6a...363dd58ba231feb301e9c760c2b2ea8632eb28f4)

[Herschel]

Very helpful, thanks!

[Herschel]

Better error supplied in #1458.

[Padre2]

Hello,

I want to use Ruffle on a hosted server that uses Litespeed.
I have tried it on my localhost LAMP server after adding AddType application/wasm .wasm to the hppd.conf file.
After adding the path for the script the SWF files ran well on first try.
I did not have success with the Litespeed server and got a Ruffle error message.
Is there any information available about using with Litespeed?