[SOLVED] Error after J3.6.4 update: Error decoding JSON data: unexpected end of data

Hi, after update to J3.6.4, i get in administrator when trying to access content items :
Error decoding JSON data: unexpected end of data
I tried to update to FC3.1.0.
No change...

Browser cache and site cache cleared without any change...
Any clue ?
Thanks
Xavier

Ok.
If i try to access to all content in the admin, i get the error.
I i acces the categories and then click on the number showing the number of items, i can have the list, modifying, etc..
But if i removed all the filter, i have then the error.
???

Hello

- J3.6.4 has changed the code and when a bad JSON string is encountered, and it will throw an exception
(and if extension does not catch the exception, the page breaks)

There is long discussion about it in Joomla issue tracker:
github.com/joomla/joomla-cms/issues/12460

To get more info e.g. for Joomla backend if using ISIS Template:
edit file:
administrator/templates/isis/error.php

Find:

and after it add:
This way we can know where the error has occured

Hello

actually you only need to enable "DEBUG" in Joomla global configuration

and then visit the page that should tell us where the error is thrown
- copy paste here the "Trace" that will be printed

Hi Georges,
First, after modifying isis error page, i get with the debug (replace my site name by "mysite" :

0 Error decoding JSON data: unexpected end of data
72 /var/www/vhosts/mysite.com/httpdocs/libraries/vendor/joomla/registry/src/Format/Json.php

Call stack
# Function Location
1 JApplicationCms->execute() /var/www/vhosts/mysite.com/httpdocs/administrator/index.php:51
2 JApplicationAdministrator->doExecute() /var/www/vhosts/mysite.com/httpdocs/libraries/cms/application/cms.php:261
3 JApplicationAdministrator->dispatch() /var/www/vhosts/mysite.com/httpdocs/libraries/cms/application/administrator.php:152
4 JComponentHelper::renderComponent() /var/www/vhosts/mysite.com/httpdocs/libraries/cms/application/administrator.php:98
5 JComponentHelper::executeComponent() /var/www/vhosts/mysite.com/httpdocs/libraries/cms/component/helper.php:380
6 require_once() /var/www/vhosts/mysite.com/httpdocs/libraries/cms/component/helper.php:405
7 require_once() /var/www/vhosts/mysite.com/httpdocs/administrator/components/com_flexicontent/flexicontent.php:22
8 JControllerLegacy->execute() /var/www/vhosts/mysite.com/httpdocs/administrator/components/com_flexicontent/admin.flexicontent.php:291
9 FlexicontentController->display() /var/www/vhosts/mysite.com/httpdocs/libraries/legacy/controller/legacy.php:702
10 JControllerLegacy->display() /var/www/vhosts/mysite.com/httpdocs/administrator/components/com_flexicontent/controller.php:323
11 FlexicontentViewItems->display() /var/www/vhosts/mysite.com/httpdocs/libraries/legacy/controller/legacy.php:664
12 JViewLegacy->get() /var/www/vhosts/mysite.com/httpdocs/administrator/components/com_flexicontent/views/items/view.html.php:362
13 FlexicontentModelItems->getData() /var/www/vhosts/mysite.com/httpdocs/libraries/legacy/view/legacy.php:408
14 Joomla\Registry\Registry->__construct() /var/www/vhosts/mysite.com/httpdocs/administrator/components/com_flexicontent/models/items.php:369
15 Joomla\Registry\Registry->loadString() /var/www/vhosts/mysite.com/httpdocs/libraries/vendor/joomla/registry/src/Registry.php:72
16 Joomla\Registry\Format\Json->stringToObject() /var/www/vhosts/mysite.com/httpdocs/libraries/vendor/joomla/registry/src/Registry.php:366

After reading the post you gave me, i have tried "update xxxx_modules set params="" WHERE params = "{\"\"}";" without any results..

Can give me a hand on this ?
I check other sites : no issues of this type on FC items in backend.
Only one site have the issue. The strange thing : that's not a migrated site from J1 or j2, just an update from 3.6.2 to 3.6.4...
Thanks Georges,
Xavier