httr and TLS -- sometimes it works, sometimes it doesn't - r

Question

I've been using httr to export data from REDCap databases into R for a few months now. We recently upgraded our R Studio Server to the most recent version (v0.98.1049) and upgraded to R 3.1.1 at the same time. After that upgrade, my httr::POST calls stopped working, sometimes. The error I keep getting is
Error in function (type, msg, asError = TRUE) :
GnuTLS recv error (-9): A TLS packet with unexpected length was received.
At first I thought it might be an SSL issue, but the error only occurs in certain databases, and in those databases, I can still download the data using RCurl. That is, this code will work
RCurl::postForm(uri=[URL],
.params=list(token=[TOKEN],
content='record',
format='csv'))
But this code will not
httr::POST(url=[URL],
body=list(token=[TOKEN],
content='record',
format='csv'))
Adding further to my confusion, even though I can't export data in projects where this error occurs, I can import data.
I'm out of ideas on where to start. I'd much appreciate any ideas on what might be going wrong here.
(I'd like to provide a reproducible example, but I'm afraid I'm working with healthcare data. sorry)
As requested, here's the verbose() output. It's a slightly different call, but produces the same error. (I used a call that wouldn't risk exposing confidential information)
> httr::POST(url=whi$url,
+ body=list(token=whi$token,
+ content='metadata',
+ format='csv'),
+ httr::verbose(data_in=TRUE, info=TRUE))
* Hostname was found in DNS cache
* Hostname in DNS cache was stale, zapped
* Trying 172.26.30.4...
* Connected to [URL] (172.26.30.4) port 443 (#7)
* found 153 certificates in /home/nutterb/R/x86_64-unknown-linux-gnu-library/3.1/httr/cacert.pem
* SSL re-using session ID
* server certificate verification OK
* common name: [URL] (matched)
* server certificate expiration date OK
* server certificate activation date OK
* certificate public key: RSA
* certificate version: #3
* subject: OU=Domain Control Validated,CN=[URL]
* start date: Thu, 10 Apr 2014 17:06:17 GMT
*
* expire date: Sat, 21 Mar 2015 16:35:07 GMT
*
* issuer: C=US,ST=Arizona,L=Scottsdale,O=Starfield Technologies\, Inc.,OU=http://certs.starfieldtech.com/repository/,CN=Starfield Secure Certificate Authority - G2
* compression: NULL
* cipher: AES-128-CBC
* MAC: SHA1
-> POST /redcap/api/ HTTP/1.1
-> User-Agent: curl/7.35.0 Rcurl/1.95.4.1 httr/0.5.0.9000
-> Host: [URL]
-> Accept-Encoding: gzip
-> accept: application/json, text/xml, */*
-> Content-Length: 374
-> Expect: 100-continue
-> Content-Type: multipart/form-data; boundary=------------------------05c968969cc362a9
->
<- HTTP/1.1 100 Continue
>> --------------------------05c968969cc362a9
>> Content-Disposition: form-data; name="token"
>>
>> [TOKEN]
>> --------------------------05c968969cc362a9
>> Content-Disposition: form-data; name="content"
>>
>> metadata
>> --------------------------05c968969cc362a9
>> Content-Disposition: form-data; name="format"
>>
>> csv
>> --------------------------05c968969cc362a9--
<- HTTP/1.1 200 OK
<- Date: Sat, 06 Sep 2014 09:55:43 GMT
<- Expires: 0
<- cache-control: no-store, no-cache, must-revalidate
<- Pragma: no-cache
<- Access-Control-Allow-Origin: *
<- Vary: Accept-Encoding
<- Content-Type: text/html; charset=utf-8
<- Connection: close
<- Content-Encoding: gzip
<-
<< NA
<< NA
<< NA
<< NA
<< NA
<< NA
<< NA
<< NA
<< NA
<< NA
<< NA
* GnuTLS recv error (-9): A TLS packet with unexpected length was received.
* Closing connection 7
Error in function (type, msg, asError = TRUE) :
GnuTLS recv error (-9): A TLS packet with unexpected length was received.
In addition: There were 11 warnings (use warnings() to see them)
> warnings()
Warning messages:
1: In strsplit(x, "\n", fixed = TRUE) : input string 1 is invalid in this locale
2: In strsplit(x, "\n", fixed = TRUE) : input string 1 is invalid in this locale
3: In strsplit(x, "\n", fixed = TRUE) : input string 1 is invalid in this locale
4: In strsplit(x, "\n", fixed = TRUE) : input string 1 is invalid in this locale
5: In strsplit(x, "\n", fixed = TRUE) : input string 1 is invalid in this locale
6: In strsplit(x, "\n", fixed = TRUE) : input string 1 is invalid in this locale
7: In strsplit(x, "\n", fixed = TRUE) : input string 1 is invalid in this locale
8: In strsplit(x, "\n", fixed = TRUE) : input string 1 is invalid in this locale
9: In strsplit(x, "\n", fixed = TRUE) : input string 1 is invalid in this locale
10: In strsplit(x, "\n", fixed = TRUE) : input string 1 is invalid in this locale
11: In strsplit(x, "\n", fixed = TRUE) : input string 1 is invalid in this locale
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