This is how I determined the source of the problem. On the administration, I raised the error reporting to maximum:
Global Configuration > Server tab > Error Reporting (changed from System Default to Maximum)
I saw the following errors:
Notice: Undefined variable: plugin in */home5//public_html/plugins/system/connectdaily/connectdaily.php on line 42
Fatal error: Call to a member function logError() on null in /home5//public_html/plugins/system/connectdaily/connectdaily.php on line 42*
I deactivated the connectdaily plugin. The fix worked. I am now able to add and edit articles again.
I am still not sure where the connectdaily plugin is used for. If ever the website will need it, I will just reinstall the plugin.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…