(ERROR @ /var/www/html/modx/core/xpdo/xpdo.class.php : 2414) PHP warning: json_encode() [function.json-encode]: recursion detected

I don't know when this started, but I found on one of my sites, that the modx error log is full of this error message.

[2018-09-27 11:27:00] (ERROR @ /var/www/html/modx/core/xpdo/xpdo.class.php : 2414) PHP warning: json_encode() [<a href='function.json-encode'>function.json-encode</a>]: recursion detected

I've tracked it down to saving a chunk in the manager, any chunk no matter the content. It doesn't happen with any other type of resources. It doesn't matter if I make any changes to the chunk. Each time a chunk is opened, 35+ errors are generated.

I though perhaps some plugin that activates on closing a resource my be the culprit. I disabled Version X which would make a copy of the chunk when closing, but this had no affect.

I searched the forums for this, but any references to this were from 7-8 years ago when when saving resources resulted in an infinite saving loop. TinyMCE was considered the cause.

Any thoughts on how to track this down?

Modx: 2.6.5
PHP: 5.3.3
SQL: 5.1.73
This is a private server managed by the client IT department.

I would first try repairing all tables in PhpMyAdmin.

You could also watch the network tab in Chrome or Firefox (Ctrl-shift-i), to see if that shows anything.

A problem with a plugin attached to OnChunkFormSave could do that, but it seems unlikely that you have one.

A mismatch in the date/time settings can cause trouble with saving chunks.

The only time I know of that json_encode would be called for chunks would be in the case of a chunk with something in its 'properties' field, but that would be unlikely to affect all chunks.

Thanks Bob

The IT folks say the database and date/time stamps check out.

Any other ideas?

Did the network tab show anything useful? You can click on each line with a request to connectors/index.php and see the Header and Response. Sometimes the response will have a PHP error, embedded in some confusing HTML code. The data at the end of the Header may provide a clue to which processor is being called via the connector.

The headers look fine. All of them show status of 200. When I click on them, I see no errors. I'll send the info to you privately to be sure I'm looking at the right thing.

Also I just discovered that the errors are not generated when saving a chunk, just when closing one (whether I save it first or not).

Sorry, I'm baffled. I've never seen this before. Maybe the server error logs would help.

Thanks Bob.

I'll see what they say.

Well, they see nothing out of the ordinary in the server logs. Hmmm.....

Perhaps I can try disabling plugins and snippets one at a time, maybe it'll surface.

Another thought: Take a look at the chunk table (modx_site_htmlsnippets) in PhpMyAdmin. Look at the 'properties' fields for all chunks to see if any chunk has something there.

The properties field all contain:

a:0:{}

Except there are couple that contain NULL