rss and multi-byte strings

[lainalien]

Hi all

I just went on a journey of discovery trying to get the rss and atom feeds on my blog working on my VPS. the long and short of it is that the default configuration for PHP is for the multibyte string extension to be disabled, but is used in core.language.php
idk how best to format this for the wiki, or whether it would be best to put it in the installation section, or in the rss plugin section with a link in installation, but figured the information should be somewhere.

on a fresh install of flatpress 1.4 to my lamp server (ubuntu 24.04, php 8.3), the rss and atom feeds would return a 500 error. watching the php error logs and reloading the error page gave this stack trace:

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2026-01-16T22:44:30.944253-05:00 wired-navi php: PHP Fatal error:  Uncaught Error: Call to undefined function mb_check_encoding() in /var/www/html/lainalien.space/public_html/blog/fp-includes/core/core.language.php:446
2026-01-16T22:44:30.944500-05:00 wired-navi php: Stack trace:
2026-01-16T22:44:30.944535-05:00 wired-navi php: #0 /var/www/html/lainalien.space/public_html/blog/fp-content/compile/e93fccb09cf8b04111b9595da102f3f4^9516bb53639f944ce0fd43441f1cc2a695da276c_0.file.rss.tpl.php(99): fix_encoding_issues()
2026-01-16T22:44:30.944574-05:00 wired-navi php: #1 /var/www/html/lainalien.space/public_html/blog/fp-includes/smarty-4.5.5/libs/sysplugins/smarty_template_resource_base.php(123): content_69225e65273ad5_34326260()
2026-01-16T22:44:30.944610-05:00 wired-navi php: #2 /var/www/html/lainalien.space/public_html/blog/fp-includes/smarty-4.5.5/libs/sysplugins/smarty_template_compiled.php(114): Smarty_Template_Resource_Base->getRenderedTemplateCode()
2026-01-16T22:44:30.944641-05:00 wired-navi php: #3 /var/www/html/lainalien.space/public_html/blog/fp-includes/smarty-4.5.5/libs/sysplugins/smarty_internal_template.php(217): Smarty_Template_Compiled->render()
2026-01-16T22:44:30.944676-05:00 wired-navi php: #4 /var/www/html/lainalien.space/public_html/blog/fp-includes/smarty-4.5.5/libs/sysplugins/smarty_internal_templatebase.php(238): Smarty_Internal_Template->render()
2026-01-16T22:44:30.944708-05:00 wired-navi php: #5 /var/www/html/lainalien.space/public_html/blog/fp-includes/smarty-4.5.5/libs/sysplugins/smarty_internal_templatebase.php(134): Smarty_Internal_TemplateBase->_execute()
2026-01-16T22:44:30.944732-05:00 wired-navi php: #6 /var/www/html/lainalien.space/public_html/blog/index.php(223): Smarty_Internal_TemplateBase->display()
2026-01-16T22:44:30.944760-05:00 wired-navi php: #7 /var/www/html/lainalien.space/public_html/blog/index.php(231): index_display()
2026-01-16T22:44:30.944787-05:00 wired-navi php: #8 {main}
2026-01-16T22:44:30.945009-05:00 wired-navi php:   thrown in /var/www/html/lainalien.space/public_html/blog/fp-includes/core/core.language.php on line 446

mb_check_encoding() is provided by a multibyte string extension which, according to the php documentation, is not enabled by default. to check if it was i looked at my phpinfo(); page and saw in my case that "Zend Multibyte Support" was disabled (troubleshooting pages i found around didnt mention zend but had similar lines).

to enable multibyte support, i had to install the mbstring extension, php-mbstring

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sudo apt install php-mbstring

and then enable it in php.ini. my configuration is largely the default provided by my vps, which matches my own local config's layout according to line numbers. Zend Multibyte Support can be enabled by setting zend.multibyte to True (commented out on line 376) and enabling extension=multistring (cummented out on line 948). then just reload apache with

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sudo /etc/init.d/apache2 reload

reloading the phpinfo page now shows that multibyte support is "provided by mbstring", and rss and atom feeds now work as expected

[fraenkiman]

Hello lainalien,

Welcome to the support forum. Thank you for your feedback regarding the dependency on the multibyte string extension in FlatPress 1.4 -> core.language.php -> function fix_encoding_issues(). Since the feed plugin is part of Ditrobotion, I think
a note here is appropriate.

I have also created an issue.

Thank you very much and best regards,
Frank

[fraenkiman]

Hello lainalien,

I have included a fix for this issue in the current master branch. Could you please run a test? I have sent you the details via private message.

Many thanks.
Frank

[fraenkiman]

Thank you for the test.
Merged for RC2.

Good night.
Frank