PHP Fatal Error: Declaration of MWCallbackStream::write($string) must be compatible with Psr\Http\Message\StreamInterface::write(string $string): int
MediaWiki 1.43 and php 8.2.
https://github.com/wikimedia/mediawiki/commit/5a6838829c4c63215d4e622164ce29e15c7024d0 upgraded psr/http-message to 1.1 which did https://github.com/php-fig/http-message/commit/cb6ce4845ce34a8ad9e68117c10ee90a29919eba.
Change #1128036 had a related patch set uploaded (by Paladox; author: Paladox):
[mediawiki/core@master] MWCallbackStream: Fix "Declaration of MWCallbackStream::write($string) must be compatible with Psr\Http\Message\StreamInterface::write"
I fixed it locally. An extension had a newer http-message version. We use a tool to deploy mw. So the version I was looking at was different to the one on another server. I eventually found the cause. And re-deployed the extension with the correct version.
The linked change can still be merged.
Change #1128036 abandoned by Paladox:
[mediawiki/core@master] MWCallbackStream: Fix "Declaration of MWCallbackStream::write($string) must be compatible with Psr\Http\Message\StreamInterface::write(string $string)"