Sounds like PHP issue. How about restarting Apache. https://github.com/roundcube/roundcubemail/issues/8544

assuming the upgrade went smoothly and the file is present in program\lib\Roundcube\ have you checked the permissions?

Hi all,

PHP 7.4.32

after upgrading from 1.4.15 LTS to 1.5.12 LTS i get this on some emails (not all), the error show opening emails  with "simple" content eg. the ones with text and one or 2 lines as body eg. the test email from the Roundcube installer.

Details:

[13-Jan-2026 21:02:08 Europe/Rome] PHP Fatal error:  Uncaught IntlException: fopen(rcmail_string_replacer.php): failed to open stream: Bad file number in D:\apache\htdocs\webmail\program\lib\Roundcube\bootstrap.php:443
Stack trace:
#0 D:\apache\htdocs\webmail\program\lib\Roundcube\bootstrap.php(443): fopen('rcmail_string_r...', 'r', true)
#1 [internal function]: rcube_autoload('rcmail_string_r...')
#2 D:\apache\htdocs\webmail\program\lib\Roundcube\rcube_text2html.php(145): spl_autoload_call('rcmail_string_r...')
#3 D:\apache\htdocs\webmail\program\lib\Roundcube\rcube_text2html.php(130): rcube_text2html->_converter(NULL)
#4 D:\apache\htdocs\webmail\program\lib\Roundcube\rcube_text2html.php(110): rcube_text2html->_convert()
#5 D:\apache\htdocs\webmail\program\actions\mail\index.php(1102): rcube_text2html->get_html()
#6 D:\apache\htdocs\webmail\program\actions\mail\show.php(742): rcmail_action_mail_index::plain_body(NULL)
#7 D:\apache\htdocs\webmail\program\include\rcmail_output_html.php(1484): rcmail_action_ in D:\apache\htdocs\webmail\program\lib\Roundcube\bootstrap.php on line 443


I also had the issue oops, internal error and i had to copy jquery.ui.datepicker-it.js to jquery.ui.datepicker-it.min.js under \plugins\jq... to fix this.

Of course i've not found any info/fix about the "bad file number" issue.

Eg. The content of one of the emails that show the issue:

"

MIME-Version: 1.0
From: [email protected]
To: [email protected]
Subject: Test message from Roundcube
Message-ID: <0066020880.00006X6I@srv2>
Date: Tue, 13 Jan 2026 18:20:20 -0000
X-Date-Added: Date header was added by srv2


This is a test to confirm that Roundcube can send email.

"


thanks for any help

massimo

Hello friends,

I have Roundcube and v 5.1.2 of RCMCardDav installed on my shared hosting server.

I have a Google account set up for a community organization and have our members details in the Google Contacts application.

What is the correct (and successful) way to access the contacts in Roundcube (via DAV)? I could not find any documentation. Despite following various "solutions" and suggestions, I am unable to get this working. So far, whatever I try, I always get the error "Could not determine the addressbook home".

Any configuration/setup tips would be most welcome. Or, if there is a doc or KB on this somewhere, please point me in the right direction.

Thanks in advance.

Check the error log (Roundcube or web server  or php-fpm).

Hello, I'm a Japanese IT professional working on a Roundcube project for the first time. When I create an email and save it as a draft with an attachment containing more than 21 Japanese characters, the file name is displayed, but it shows as 0 bytes, and the email subject is not displayed. When a received email contains an attachment containing more than 21 Japanese characters, the email list displays the subject and a paperclip indicating the attachment, but when I open it, I get an error message saying [oops]. My IMAP server is the e-post mail server. Connecting to the e-post mail server via IMAP with Thunderbird works fine. Also, connecting to Devcot as a test works fine. I'd appreciate any advice on how to resolve this issue.

What is in your browser JS console?

What is your Nginx config?

Hello team

i am beginner on this platform but i need to share my issue so i can get an help

i have an issue on my Roundcube 1.6 which i configured on Ubuntu server 24 as webmail (Nginx) and what is concerning is;

when i access it on the browser it display normal HTML and not Roundcube UI so seems is like it can load the static file.

So how could I resolve this issue if anyone know or encounter this issue am here to listen

Hi Gene!

I fully agree that the CardDAV plugin is working really well and that there is no need for something similar. However on the CalDAV side, I have to admit that - as many others - I am just not able to get that damn plugin to work. And what makes it even worse, I have no clue where to troubleshoot. The plugin works well as long as I use database as the backend. Whenever I enable caldav as the calendar driver, I just get an "Ooops, something went wrong!" page :-( error.log is empty and I have to idea where to start debugging.

Saying that, an easy to install and configure CalDAV plugin would make my day.

Thanks for your work anyway!
best regards,
Marcus.

It's no wonder you're a hero member! It helped!

Thank you!