The legacy Dashio Issue Tracker list returned HTTP 200 for a user holding only issuetracker_view, but DataTables failed during initialization. The read-only page had three visible column headers and four cells in every tracker row, so the browser raised TypeError: Cannot read properties of undefined (reading 'mData'). The DataTables search box and the configured page-size control were not rendered.

The management path still rendered, so the failure was limited to the read-only column contract. This is the second of three sibling templates with the same defect: the Code Tracker one was fixed in #1582, this one in #1584, and the Requirement Manager one is tracked in #1585.

Entry point: http://localhost:8082/lib/issuetrackers/issueTrackerView.php?tproject_id=1.

• TestLink 2.0.1 with PHP 8.3 and MariaDB on the local CI instance, docroot = repository root, PHP built-in server on port 8082.
• The freshly imported database contained 0 test projects and 0 issue trackers — exactly the condition under which the original reporter could not live-reproduce the defect. The fixture below was recreated for this run.
• Test project 1: Issue1584 Fixture (nodes_hierarchy id 1 → testprojects id 1, issue_tracker_enabled = 1).
• Issue trackers: 1 IT1584 Redmine (type 15), 2 IT1584 Mantis (type 3), 3 IT1584 GitHub (type 25).
• Project link: (testproject_id=1, issue_tracker_id=2). Note that testproject_issuetracker has PRIMARY KEY (testproject_id) alone, so only one tracker can be linked per project. Result: IT1584 Mantis has link_count = 1 and the other two have link_count = 0, which exercises the delete gate in both directions.
• ro_tracker: global role 10 issue1584 read-only holding exactly right 32 (issuetracker_view) and no right 31 (issuetracker_management), assigned to project 1 through user_testproject_roles.
• admin: global role 8, holds both tracker rights.

1. Recreate the fixture above.
2. Log in as ro_tracker / admin.
3. Open the entry point with a cache-bypassing navigation.
4. Inspect the table structure, DataTables controls and the browser console.

Measured pre-fix result:

• The document response was HTTP 200 and the PHP side was healthy (all three trackers rendered with name, type and environment).
• The table had 3 headers: Issue Tracker, Type, Environment.
• Every populated row had 4 cells (rowCellCounts: [4,4,4]).
• DataTables did not initialize (dtWrapper: false), the page-length menu was empty (lengthSelect: []) and no search box was rendered.
• Chrome reported one uncaught TypeError: Cannot read properties of undefined (reading 'mData') plus the associated jQuery Deferred warning, with the stack terminating in DataTables 1.12.1 and at the generated page line issueTrackerView.php:275 (the DataTables.inc.tpl include).
• The Event Viewer gained no Error/Warning row from this defect: it is a client-side column-contract failure, not a PHP failure.

The pre-fix state is preserved as issue-1584-before.png.

1. lib/issuetrackers/issueTrackerView.php:23-24 loads tracker rows (including link_count) and sets $gui->canManage from issuetracker_management; checkRights() at :64-65 admits the page to a user holding only issuetracker_view. The mismatch is therefore reachable by design.

2. gui/templates/dashio/issuetrackers/issueTrackerView.tpl:45-47 renders the delete column header only when $gui->canManage is non-empty.

3. Before the fix, issueTrackerView.tpl:78-85 rendered the delete body cell unconditionally:

   <td class="clickable_icon">                                  <!-- 78 -->
     {if $gui->canManage != ""  && $item_def.link_count == 0}    <!-- 79 -->
       <i class="fas fa-minus-circle" ...></i>
     {/if}
   </td>                                                         <!-- 84 -->
   </td>                                                         <!-- 85 stray -->

   The permission check was written to guard the delete icon; it was never lifted to the enclosing <td>. Line 85 is a second closing tag for the same cell, so the HTML parser appends a fourth, empty cell rather than merely mis-aligning the row.

4. issueTrackerView.tpl:26-29 includes DataTables.inc.tpl for #item_view whenever the list is populated. DataTables maps columns from the 3 <th>; the 4th <td> resolves to undefined, producing the mData TypeError and aborting initialization.

The unconditional cell and the stray </td> are inherited 1.9.20 defects, not a recent regression. They only became structurally visible when the Environment column was inserted in front of them at issueTrackerView.tpl:77. Before that column existed, both clickable_icon cells sat at the end of the row, so the trailing empty cell was visually harmless. Adding a column ahead of them turned the 3-vs-4 header/cell mismatch into a hard DataTables error — the same reason the identically shaped Code Tracker template failed in #1582.

gui/templates/dashio/issuetrackers/issueTrackerView.tpl — one file, +9 / -8:

         <td>{$item_def.type_descr|escape}</td>
         <td class="clickable_icon">{$item_def.env_check_msg|escape}</td>
-          <td class="clickable_icon">
-            {if $gui->canManage != ""  && $item_def.link_count == 0}
-              <i class="fas fa-minus-circle" title="{$labels.testproject_alt_delete}" 
-                 onclick="delete_confirmation(...)"></i>
-            {/if}
-          </td>
-        </td>  
+          {if $gui->canManage != ""}
+            <td class="clickable_icon">
+              {if $item_def.link_count == 0}
+                <i class="fas fa-minus-circle" title="{$labels.testproject_alt_delete}" 
+                   onclick="delete_confirmation(...)"></i>
+              {/if}
+            </td>
+          {/if}
       </tr>

The method chosen is the minimal structural hoist: the existing $gui->canManage condition is lifted from the icon to the cell, so header and cell are emitted from the same predicate, and the stray tag is deleted. This is byte-for-byte structurally identical to the fix accepted for the Code Tracker sibling in a548c855d (#1582), which keeps the three list templates maintainable in parallel.

The inner link_count == 0 test is deliberately kept as a separate nested condition rather than folded into the outer one, so the manager list keeps the documented behaviour: the delete column is present, and the icon is hidden for any tracker linked to at least one test project.

• Remove the delete column entirely — breaks the management workflow, and the issue explicitly requires the manager list to keep it.
• Add a fourth, empty header for read-only users — ships a meaningless column and contradicts the expected contract (three headers, three cells).
• Suppress the extra cell in JavaScript (e.g. telling DataTables to ignore it) — leaves structurally invalid HTML (4 <td> under 3 <th>) in the DOM. The correct repair point is the template.
• Hoist the condition into a <tbody>-level or per-foreach variable — more churn for no behavioural gain.

No PHP, API or i18n changes were required: the defect was purely server-side Smarty, inc_del_onclick.tpl still supplies delete_confirmation, and no JavaScript dereferences the cell.

Read-only user ro_tracker (issuetracker_view only):

Administrator:

The corrected read-only and management states are preserved as issue-1584-after-readonly.png and issue-1584-after-admin.png.

Additional regression cases exercised: the empty-list path ($gui->items == '' skips the DataTables include — header-only table, no <tbody>, no console error, no new Event Viewer row), and anonymous access in a fresh isolated browser context, which is redirected to login.php?note=expired&destination=… without ever rendering the list.

The generated-PHP lint of the recompiled template is clean, and the sibling templates were confirmed untouched (git diff --stat shows only issuetrackers/issueTrackerView.tpl).

Regression suite: tmp/TLU_Test_Cases.md, entry Regression — Issue #1584, 8/8 PASS.

Two further pre-existing defects were found while verifying this fix and were filed separately rather than silently folded in:

• #1590 — issueTrackerView.tpl:81 renders the delete icon tooltip with {$labels.testproject_alt_delete}, but the template's {lang_get} at :12-16 loads alt_delete. Result: an empty tooltip plus two E_WARNING Undefined array key rows per manager page load. The sibling codeTrackerView.tpl uses the correct {$labels.alt_delete}. Introduced with the Dashio theme port, not by this change.
• #1591 — config.inc.php never defines $tlCfg->gui->{issueTrackerView,codeTrackerView,reqMgrSystemView}->pagination, so issueTrackerView.tpl:27 dereferences a missing object, logging three E_WARNINGs per load and leaving the page-size <select> with zero options. This is why the page-length menu is still empty after this fix even though DataTables now initializes correctly.

reqMgrSystemView.tpl:71-77 still carries the same cell/header mismatch and is tracked by the still-open issue #1585.