Recoverable fatal error: Object of class stdClass could not be converted to string in panels_simple_cache_get_id()

Recoverable fatal error: Object of class stdClass could not be converted to string in panels_simple_cache_get_id() (line 112 of /sites/all/modules/contrib/panels/plugins/cache/simple.inc).

I am receiving this issue as well. Has there been any movement?

Same here, error still present in 7.x-3.7, but...
My case:
- a block issued by a views view listing 5 items of same type as the one in main content, excepted the one in content (excluded by a views contextual filter)
- this block is placed at second sidebar of the default site template panel page (admin/structure/pages, panels 7.x-3.7)
- block settings at template panel page "content:nid" = "content ID" (that is sent to my contextual filter)

Thinking this setting was an argument, I set the bock cache (at template panel page) granularity to "arguments". This provoked the above error and a white page.

Setting granularity to "none" doesn't provoke an error but it's not what I wanted as this keeps the same block whatever my "content ID" is and thus making useless my exclusion of the main content from the listing. So I tried to see what happens with granularity set to "context" and it worked !

Conclusion: my "content ID" is not seen by the panel page as an "argument" but as a "context" which in final analysis is correct. In views construction of the block "content ID" is a "contextual filter".

Conclusion 2: even if "context" seems correct, this situation leads user to confuse "argument" and "context". Is a parameter an argument or a context ? Welcome to a byzantine discussion about angel's gender.

Conclusion 3: Nevertheless, there is a problem with the error thrown if we set "argument" where it should be "context" and the is no other warning that our settings are wrong.

Hope it helps resolution

still present in 7.x-3.9