6.3 block themes require index.php if current theme is not block based

[dgaidula]

If the currently activated theme is not block based, WP 6.3 will report all block based themes as broken until adding an empty index.php at root of theme. This appears to be related to the new '$this->is_block_theme()' check introduced into class-wp-theme.php with 6.3+. I rolled back to WP 6.2.3 and non-block based and block-based themes can co-exist without the warning. The error message thrown is non-obvious what to fix since the perfectly functioning block-based themes 2023 1.2 include suddenly break with message about missing files that aren't missing.

[rajinsharwar]

Hi @dgaidula, thanks for your ticket. I have my site at WP 6.3.1. I activated my non-block-based theme and then installed the TT3 theme (Which is a block theme). But, I didn't notice any such issues you mentioned. Is there any step I missed?

[dgaidula]

Did you try going to Appearance > Themes after doing installing TT3?

[dgaidula]

just tested this again and it seems to be related to Roots/sage 9.0 theme. If I remove this theme then the block-based themes work correctly without the additional index.php. Sorry for wasting your time, thanks for verifying.

[rajinsharwar]

No issues, glad that you found the issue :)