In our Plone 5 Sites we have the problem, that we can not create and upload file oder image objects, when the uploaded files/images are larger than 500kb. But we need to be able to upload bigger files.
The max_file_size in the atcontenttypes.conf.in is set to "no". This might have no influence, as we use dexerity types. I could not find any config file that sets a max size limit for files/images in plone.dexterity or anywere else.
As it works fine in our PLONE 4 sites, it is not the case that the webserver would limit the upload sizes.
I am not aware of any limitations inside Plone.
Your frontend server has possibly some limitations configured...pretty of seen with Nginx but never with such a low limit...try to upload the content directly into Plone by bypassing any component in between the request.
Yeah 500K is very small, much smaller than anything I've seen before. For me, nginx limits would hit above some number of megabytes, and was easily fixed. You don't say what kind of stack you have in front of Plone.
In meantime I found out, that the problem seems not to be a PLONE problem, indeed. But still it is strange:
The Problem occures in some of our PLONE Sites, but it is no Problem in other ones of the PLONE Sites, that we have. It is independent of the PLONE Version (we have 3,4,5).
We use Apache and the error logs, were the Problem occurs says on every upload try with files >500kb:
[error] (70007)The timeout specified has expired: proxy: prefetch request body failed to 127.0.0.1:8099 (127.0.0.1) from 217.252.55.98 ()
And sometimes, but not always:
[error] proxy: pass request body failed to 127.0.0.1:8099 (127.0.0.1) from 217.252.55.98 ()
Andreas, the strage thing is, that the problem always occurs, when I call a site by its portnumer instead of its domain name, thus bypassing the Apache server, that we use. If I call the same site with its domain name, it works fine (as said for some of our sites, not for all of them).
We have now asked our provider, who hosts our server, to check the thing. But, maybe - even if it seems not to be a PLONE problem - some of you might have an idea about that.
In meantime we found out that the problem occurs when the site is not ssl instrumented. Some of our new PLONE 5 Sites did not yet run under https, so we got this Problem with them (and thought, it would be a PLONE 5 Problem).
After we have created zertificates for them and configurated Apache für https for them, the problem disappered and we could also upload very big files.
(That was also the reason, that the problom occurred also with some of our Plone3 or Plone4 Sites, when we called them directly, instead thru Apache, in which case they were not ssl-protected.)
Were the time limit for non-ssl sites comes from is subject to check with our webserver provider.