aws-sdk-php: Issue with MultipartUpload in >= 3.34.2. Getting timeout response.

I am using the league/flysystem to run upload to S3 using upload method. In 3.34.2 we are getting these errors from S3:

The operation is basically reading from a url (opening a stream) which is then passed to the S3. This does not seem to happen all the time but at least 1/5 times. We are not passing any custom parameters (defaults are used)

OS: Amazon Linux AMI release 2016.03 Curl: curl 7.49.1 (x86_64-pc-linux-gnu) libcurl/7.49.1 NSS/3.24 Basic ECC zlib/1.2.8 Php: 7.0.9 (running php-fpm)

Note the curl 35 error. Not sure if that would be the issue, or just a derivative

(Note: for clarity https/http prefixes were removed (they are not missing i.e. 😕/s3.* = https//s3.*))

Uncaught Exception Aws\S3\Exception\S3MultipartUploadException: "An exception occurred while uploading parts to a multipart upload. The following parts had errors: - Part 3: Error executing "UploadPart" on "://s3.amazonaws.com/yyy/xxx/data/Approved/CD_3945_20170826185935.pdf?partNumber=3&uploadId=IQt.rBjwmGBoFD8_R_N_6lmYX3NObVG5pXgf9Bsooh7pqyVnDg994UiQI4I24BkuWFrwpbhf11BeapNryY8LJgY8E6uRkSoKy9wF8rUX0TClAddp.usiwYjh_IYFuMUB"; AWS HTTP error: cURL error 35: Encountered end of file (see ://curl.haxx.se/libcurl/c/libcurl-errors.html) - Part 2: Error executing "UploadPart" on "://s3.amazonaws.com/yyy/xxx/data/Approved/CD_3945_20170826185935.pdf?partNumber=2&uploadId=IQt.rBjwmGBoFD8_R_N_6lmYX3NObVG5pXgf9Bsooh7pqyVnDg994UiQI4I24BkuWFrwpbhf11BeapNryY8LJgY8E6uRkSoKy9wF8rUX0TClAddp.usiwYjh_IYFuMUB"; AWS HTTP error: cURL error 35: Encountered end of file (see ://curl.haxx.se/libcurl/c/libcurl-errors.html) - Part 1: Error executing "UploadPart" on "://s3.amazonaws.com/yyy/xxx/data/Approved/CD_3945_20170826185935.pdf?partNumber=1&uploadId=IQt.rBjwmGBoFD8_R_N_6lmYX3NObVG5pXgf9Bsooh7pqyVnDg994UiQI4I24BkuWFrwpbhf11BeapNryY8LJgY8E6uRkSoKy9wF8rUX0TClAddp.usiwYjh_IYFuMUB"; AWS HTTP error: Client error: PUT ://s3.amazonaws.com/yyy/xxx/data/Approved/CD_3945_20170826185935.pdf?partNumber=1&uploadId=IQt.rBjwmGBoFD8_R_N_6lmYX3NObVG5pXgf9Bsooh7pqyVnDg994UiQI4I24BkuWFrwpbhf11BeapNryY8LJgY8E6uRkSoKy9wF8rUX0TClAddp.usiwYjh_IYFuMUB resulted in a 400 Bad Request response: RequestTimeoutYour socket connection to the server w (truncated...) RequestTimeout (client): Your socket connection to the server was not read from or written to within the timeout period. Idle connections will be closed. - RequestTimeoutYour socket connection to the server was not read from or written to within the timeout period. Idle connections will be closed.F5E729A38A40DC4Btg62PcN1ACjdUQsGBFY1SNUDOdc0CRJ3BowcTgAcg5cavdFm70k/VxsNxC4sNTwdcKm6XAEVRtg= " at /srv/www/vendor/aws/aws-sdk-php/src/Multipart/AbstractUploadManager.php line 127 {"exception":"[object] (Aws\S3\Exception\S3MultipartUploadException(code: 0): An exception occurred while uploading parts to a multipart upload. The following parts had errors:\n- Part 3: Error executing \"UploadPart\" on \"://s3.amazonaws.com/yyy/xxx/data/Approved/CD_3945_20170826185935.pdf?partNumber=3&uploadId=IQt.rBjwmGBoFD8_R_N_6lmYX3NObVG5pXgf9Bsooh7pqyVnDg994UiQI4I24BkuWFrwpbhf11BeapNryY8LJgY8E6uRkSoKy9wF8rUX0TClAddp.usiwYjh_IYFuMUB\"; AWS HTTP error: cURL error 35: Encountered end of file (see ://curl.haxx.se/libcurl/c/libcurl-errors.html)\n- Part 2: Error executing \"UploadPart\" on \"://s3.amazonaws.com/yyy/xxx/data/Approved/CD_3945_20170826185935.pdf?partNumber=2&uploadId=IQt.rBjwmGBoFD8_R_N_6lmYX3NObVG5pXgf9Bsooh7pqyVnDg994UiQI4I24BkuWFrwpbhf11BeapNryY8LJgY8E6uRkSoKy9wF8rUX0TClAddp.usiwYjh_IYFuMUB\"; AWS HTTP error: cURL error 35: Encountered end of file (see ://curl.haxx.se/libcurl/c/libcurl-errors.html)\n- Part 1: Error executing \"UploadPart\" on \"://s3.amazonaws.com/yyy/xxx/data/Approved/CD_3945_20170826185935.pdf?partNumber=1&uploadId=IQt.rBjwmGBoFD8_R_N_6lmYX3NObVG5pXgf9Bsooh7pqyVnDg994UiQI4I24BkuWFrwpbhf11BeapNryY8LJgY8E6uRkSoKy9wF8rUX0TClAddp.usiwYjh_IYFuMUB\"; AWS HTTP error: Client error: PUT ://s3.amazonaws.com/xxx/yyy/data/Approved/CD_3945_20170826185935.pdf?partNumber=1&uploadId=IQt.rBjwmGBoFD8_R_N_6lmYX3NObVG5pXgf9Bsooh7pqyVnDg994UiQI4I24BkuWFrwpbhf11BeapNryY8LJgY8E6uRkSoKy9wF8rUX0TClAddp.usiwYjh_IYFuMUB resulted in a 400 Bad Request response:\n\nRequestTimeoutYour socket connection to the server w (truncated...)\n RequestTimeout (client): Your socket connection to the server was not read from or written to within the timeout period. Idle connections will be closed. - \nRequestTimeoutYour socket connection to the server was not read from or written to within the timeout period. Idle connections will be closed.F5E729A38A40DC4Btg62PcN1ACjdUQsGBFY1SNUDOdc0CRJ3BowcTgAcg5cavdFm70k/VxsNxC4sNTwdcKm6XAEVRtg=\n at /srv/www/vendor/aws/aws-sdk-php/src/Multipart/AbstractUploadManager.php:127)"}