RT 5.0.9 and previous versions.
I couldn’t open a Lifecycle for edit if the language UI wasn’t set to English.
File $RT_HOME/share/html/Admin/Lifecycles/index.html, line 79:
<td class="collection-as-table"><a href="<% RT->Config->Get('WebURL') %>Admin/Lifecycles/Modify.html?Type=<% $lifecycles{$key}{'type'} ? loc($lifecycles{$key}{'type'}) : loc('ticket') |u %>&Name=<% $key %>"><% $key %></a></td>
The URL mustn’t be translated, so I’ve changed this line to:
< <td class="collection-as-table"><a href="<% RT->Config->Get('WebURL') %>Admin/Lifecycles/Modify.html?Type=<% $lifecycles{$key}{'type'} ? $lifecycles{$key}{'type'} : 'ticket' |u %>&Name=<% $key %>"><% $key %></a></td>
Now the error is gone. I don’t know if this is happening in RT 6.x