ThemeCheck warning: critical alert

[thlinard]

http://themecheck.org/ said:

Screenshot size is 880x660px. Screenshot size should be 1200x900, to account for HiDPI displays. Any 4:3 image size is acceptable, but 1200x900 is preferred.

[bdthemes]

png image not supported, jpg is working well. maximum theme screenshot used as png so why you show it as an error?

[thlinard]

I rechecked today, and it's true, the complete message is: "Screenshot : Screenshot file
Screenshot size is 880x660px. Screenshot size should be 1200x900, to account for HiDPI displays. Any 4:3 image size is acceptable, but 1200x900 is preferred.
Bad screenshot file extension ! File screenshot.png is not an actual JPG file. Detected type was : "image/png"."

The specifications require 1200x900. Further readings:
https://core.trac.wordpress.org/ticket/34806
https://make.wordpress.org/themes/2015/10/06/screenshot-clarification-update/

I don't understand the problem with a PNG file. https://codex.wordpress.org/Theme_Development said:
"Screenshot

Create a screenshot for your theme. The screenshot should be named screenshot.png, and should be placed in the top level directory. The screenshot should accurately show the theme design and saved in PNG format. The recommended image size is 1200x900. The screenshot will only be shown as 387x290, but the over double-sized image allows for high-resolution viewing on HiDPI displays.

Note that optionally, .jpg, .jpeg, and .gif are also valid extensions and file formats for the screenshot (though not recommended)."

But perhaps it's an outdated documentation.

[bdthemes]

@thlinard yes you are right.

[thlinard]

New validation:

Critical alerts

Inapropriate constants : Use of HEADER_TEXTCOLOR
Constant HEADER_TEXTCOLOR was found in the file custom-header.php. add_theme_support( 'custom-header' ) should be used instead.
Line 38: // get_header_textcolor() options: HEADER_TEXTCOLOR is default, hide text (returns 'blank') or any hex value
Line 39: if ( HEADER_TEXTCOLOR == $header_text_color ) {

Warning

theme tags : Presence of bad theme tags
The tag white has been deprecated, it must be removed from style.css header.
The tag black has been deprecated, it must be removed from style.css header.
The tag blue has been deprecated, it must be removed from style.css header.
The tag light has been deprecated, it must be removed from style.css header.
The tag responsive-layout has been deprecated, it must be removed from style.css header.
Themes that use the tag accessibility-ready will need to undergo an accessibility review.
See https://make.wordpress.org/themes/handbook/review/accessibility/

Screenshot : Screenshot file
Screenshot size is 880x660px. Screenshot size should be 1200x900, to account for HiDPI displays. Any 4:3 image size is acceptable, but 1200x900 is preferred.
Bad screenshot file extension ! File screenshot.png is not an actual JPG file. Detected type was : "image/png".