I faced a similar issue with occasional errors, the cause of mine was some PHP resource settings. In particular "max_input_time" was set to the default of 30 seconds, it needed to be increased to avoid timeouts when writing files
I was having an issue with S3 not allowing me to install items through the Marketplace. I would get a "There was a problem loading this content" error.
I believe the issue was related to my CORS config as it was resolved after including "PUT" and "POST" in AllowedMethods[]
[
{
"AllowedHeaders": [
"*"
],
"AllowedMethods": [
"HEAD",
"GET",
"PUT",
"POST"
],
"AllowedOrigins": [
"*"
],
"ExposeHeaders": [],
"MaxAgeSeconds": 3000
}
]
Unsure if anyone else has run into this, or if this is the ideal setup for CORS, but it seems to have resolved the issue.
kotaco's post in Intermittent Error 500 was marked as the answer