[Error Message] Undefined variable $search_thread

[netllama]

Greetings,
I'm running myBB-1.8.32 on a Linux server.  Everything works fine when using php-7.4.33.  However, as soon as I update to php-8.0.x (or 8.1.x) every page load of the myBB forum triggers the following error message:

Type: 2
File: showthread.php(1617) : eval()'d code (Line no. 60)
Message
Undefined variable $search_thread
Back Trace: #0 /var/www/html/dv/inc/class_error.php(229): errorHandler->email_error(2, 'Undefined varia...', 'showthread.php(...', 60)
#1 /var/www/html/dv/inc/class_error.php(153): errorHandler->error(2, 'Undefined varia...', 'showthread.php(...', 60)
#2 /var/www/html/dv/showthread.php(1617) : eval()'d code(60): errorHandler->error_callback(2, 'Undefined varia...', '/var/www/html/d...', 60)
#3 /var/www/html/dv/showthread.php(1617): eval()

As php-7.x has become EOL, I really need to update to an 8.x version soon to ensure timely security updates.  Is the above a known issue?  Is there any workaround for php-8.x?

thanks!

[HLFadmin]

$search_thread is defined in line 803 of showthread.php
If usergroup 'cansearch' is true, the $search_thread variable is populated with showthread_search template.
showthread template calls that variable at the end of the posts container.

I'm still running 1.8.30 using php 7.4, so I can't do more than look at the framework of its use.
This is an excellent resource for cross-referencing, always updated to show only the current version.
https://crossreference.mybb.de/nav.html?...index.html

The first place to look is if there is a problem with the showthread_search template.
You don't say whether the errors occur on default theme or custom theme.

I will look if you provide a URL.

[netllama]

Sorry for the delayed reply.

@HFLadmin

I'm seeing this problem with the default theme.

Not sure what you mean by "provide a URL". Do you mean the URL of my myBB instance ?

[Matt]

Make sure your templates have been reverted to default, you can find outdated templates at ACP > Templates & Style > Templates > Find Updated Templates.

[netllama]

Make sure your templates have been reverted to default, you can find outdated templates at ACP > Templates & Style > Templates > Find Updated Templates.

When I go there, I see:

There are currently no templates which have been updated since you last upgraded.

[HLFadmin]

1. Look to see if showthread.php is not altered.
AdminCP / Tools and Maintenance / File Verification

2. Check if modifications to showthread template.
AdminCP / Templates & Style / Templates / Default Templates / expand Showthread Templates
Click Options button and view Diff Report of showthread. Any text in template highlighted in color?

3. Verify this segment exists in the showthread template.

<tr>
 <td class="tfoot">
 {$search_thread}
 <div>
 <strong>&laquo; <a href="{$next_oldest_link}">{$lang->next_oldest}</a> | <a href="{$next_newest_link}">{$lang->next_newest}</a> &raquo;</strong>
 </div>
 </td>
 </tr>

4. View Diff Report on showthread_search template in that same group. Any modifications?
It should look like this.

<div class="float_right">
 <form action="search.php" method="post">
 <input type="hidden" name="action" value="thread" />
 <input type="hidden" name="tid" value="{$thread['tid']}" />
 <input type="text" name="keywords" value="{$lang->enter_keywords}" onfocus="if(this.value == '{$lang->enter_keywords}') { this.value = ''; }" onblur="if(this.value=='') { this.value='{$lang->enter_keywords}'; }" class="textbox" size="25" />
 <input type="submit" class="button" value="{$lang->search_thread}" />
 </form>
 </div>

If you provide a link to your forum, I will take a look.

[Matt]

Oh actually looking at it, the variable may be undefined if searching is not allowed - have you set the permissions so that the forum can't be searched?

[HLFadmin]

There is only one place $search_thread is defined, in showthread.php

800      // Can this user perform searches? If so, we can show them the "Search thread" form
 801      if($forumpermissions['cansearch'] != 0)
 802      {
 803          eval("\$search_thread = \"".$templates->get("showthread_search")."\";");
 804      }
 805  

In the event cansearch is 0, is PHP8 calling $search_thread as undefined rather than assuming a null value?
Can test by adding a line to define it as null before performing test. Adding

$search_thread = "";

before the if statement may solve. The fix may be a core edit.

[netllama]

1. Look to see if showthread.php is not altered.
AdminCP / Tools and Maintenance / File Verification

Only admin/backups/.htaccess is listed with Status = Changed (which is expected).

2. Check if modifications to showthread template.
AdminCP / Templates & Style / Templates / Default Templates / expand Showthread Templates
Click Options button and view Diff Report of showthread. Any text in template highlighted in color?

The only option under the Options button is "Full Edit".

3. Verify this segment exists in the showthread template.

<tr>
 <td class="tfoot">
 {$search_thread}
 <div>
 <strong>&laquo; <a href="{$next_oldest_link}">{$lang->next_oldest}</a> | <a href="{$next_newest_link}">{$lang->next_newest}</a> &raquo;</strong>
 </div>
 </td>
 </tr>

It exists, and matches what you provided as lines 57-64.

4. View Diff Report on showthread_search template in that same group. Any modifications?
It should look like this.

<div class="float_right">
 <form action="search.php" method="post">
 <input type="hidden" name="action" value="thread" />
 <input type="hidden" name="tid" value="{$thread['tid']}" />
 <input type="text" name="keywords" value="{$lang->enter_keywords}" onfocus="if(this.value == '{$lang->enter_keywords}') { this.value = ''; }" onblur="if(this.value=='') { this.value='{$lang->enter_keywords}'; }" class="textbox" size="25" />
 <input type="submit" class="button" value="{$lang->search_thread}" />
 </form>
 </div>

Looks identical to what you provided on my installation.

If you provide a link to your forum, I will take a look.

Sure thing, please see https://dv.netllama.us/dv/ .

---

Oh actually looking at it, the variable may be undefined if searching is not allowed - have you set the permissions so that the forum can't be searched?

No, searching works fine on my forum, even for unauthenticated users.

---

There is only one place $search_thread is defined, in showthread.php

800      // Can this user perform searches? If so, we can show them the "Search thread" form
 801      if($forumpermissions['cansearch'] != 0)
 802      {
 803          eval("\$search_thread = \"".$templates->get("showthread_search")."\";");
 804      }
 805  

In the event cansearch is 0, is PHP8 calling $search_thread as undefined rather than assuming a null value?
Can test by adding a line to define it as null before performing test. Adding

$search_thread = "";

before the if statement may solve. The fix may be a core edit.

Adding that initialization of $search_thread before line 801 appears to fix this bug. Thank you!

What's the process for getting this fix into the official myBB code base in a future release?

---

I spoke too soon.  The original failure is gone, but now I'm getting two new failures, also inside of showthread.php:

Type: 2
File: showthread.php (Line no. 256)
Message
Undefined variable $cutoff
Back Trace: 
#0  errorHandler->email_error(2, Undefined variable $cutoff, showthread.php, 256) called at [/var/www/html/dv/inc/class_error.php:229]
#1  errorHandler->error(2, Undefined variable $cutoff, showthread.php, 256) called at [/var/www/html/dv/inc/class_error.php:153]
#2  errorHandler->error_callback(2, Undefined variable $cutoff, /var/www/html/dv/showthread.php, 256) called at [/var/www/html/dv/showthread.php:256]

Type: 2
File: showthread.php (Line no. 243)
Message
Undefined variable $lastread
Back Trace: 
#0  errorHandler->email_error(2, Undefined variable $lastread, showthread.php, 243) called at [/var/www/html/dv/inc/class_error.php:229]
#1  errorHandler->error(2, Undefined variable $lastread, showthread.php, 243) called at [/var/www/html/dv/inc/class_error.php:153]
#2  errorHandler->error_callback(2, Undefined variable $lastread, /var/www/html/dv/showthread.php, 243) called at [/var/www/html/dv/showthread.php:243]

I guess I need to initialize more variables somewhere to fix this too? 
Is there an easier way to find all the uninitialized variables at once?