Sorry change all my comments that say Chrome 72 into 73 please.

I have now found out that Google Chrome Browser has a confirmed bug!

When testing the websites in dev-tools clicking on the "Add to homescreen" button I get the following error message:

"Site cannot be installed: the manifest does not contain a suitable icon - PNG format of at least 144px is required, the sizes attribute must be set, and the purpose attribute, if set, must include "any"."

Please note I have recently changed all my icon and splash image files from .png over to .jpg

The reason for doing this was because some of my Splash image files were (compressed .png files) saying they were over 1Mb in size! Converting the image files from .png over to .jpg I reduced the file files from over 1Mb down to 200Kb. Please note, I would of converted them to webp if I was allowed.

Google usually lets the following image formats work for almost everything and these are: .gif .png and .jpg

The Google Chrome team needs to add support for allowing .jpg images to be used for icons and splash files in the manifest. This is a big performance issue and also is not helping Users on Mobile Devices with Save Data for Data Limit Plans.

Also it would be great to also add support for webp image file types for the manifest as well at a later date.

For now please can the Team add support for .jpg images in the manifest file.

Please note: Currently all the Browser vendors require the following icon sizes:

144px by 144px
192px by 192px
512px by 512px

The 512px icon and the splash images are the big issues creating the wasted data space by saying to use only .png format. This issue is probably an issue with other browsers as well.

Link to Google saying 512px is found here: https://developers.google.com/web/tools/lighthouse/audits/custom-splash-screen#recommendations

Have also opened a github issue on lighthouse repo with regards to this matter: https://github.com/GoogleChrome/lighthouse/issues/6700

Thanks for the report.

In Chrome, manifest icons are lazily loaded, and Chrome will choose and download the icon of ideal size. A 512x512px icon is not required by Chrome for a site to be a PWA. As devtools indicates, we only require a maximum 144x144px icon at the moment. In fact, in most cases, any larger icon is ignored (i.e. not even downloaded) since it's almost never currently necessary to use an icon of that size. However, future, more pixel-dense devices may require such a large icon, so supplying one is useful for future-proofing.

We currently only support PNG icons for PWAs. In general, PNG is the format of choice for high-quality app icons: both the Android Play Store and the Apple App Store require PNG icons for submitted apps, and do not accept JPEG as an alternative. We don't currently have plans to support JPEG as an app icon format. Since we typically only download a single 144x144px icon anyway, the size difference between PNG and JPG is probably not meaningful.

Support for SVG is desirable, but challenging due to decoding issues. That's tracked in Issue 578122.

We don't have any support for splash images. If you're including splash images for some other manifest reader (than Chrome), feel free to make them JPEGs, but keep your icons as PNGs.

A 512x512px PNG icon is not going to be anywhere near 1 MB. And it won't be downloaded unless the user agent thinks its necessary.