Expired Access Token

Hi Greg-DB 

Thank you for your quick response.

>>the name and version number of the platform and SDK/library you are using, if any

I'm not using SDK/library, I have made a curl function to send/receive the data from Dropbox API. I'm using the PHP Stream Wrapper class to upload and download the backup file. Below is the code snippet of the curl function

function __curl($url, $headers = '', $filepointer = '', $upload_size = 0, $post = '', $download_file = '', $ignore_errors = 0, $retry = false){
		global $error, $l;
		
		// Set the curl parameters.
		$ch = curl_init($url);
		
		if(!empty($headers)){
			curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
		}
		
		curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
		
		if(!empty($filepointer)){
			curl_setopt($ch, CURLOPT_PUT, true);
			curl_setopt($ch, CURLOPT_INFILE, $filepointer);
			curl_setopt($ch, CURLOPT_INFILESIZE, $upload_size);
		}
		
		if(!empty($post)){
			curl_setopt($ch, CURLOPT_POST, 1);
			curl_setopt($ch, CURLOPT_POSTFIELDS, $post);
		}
		//curl_setopt($ch, CURLOPT_VERBOSE, TRUE);

		// Turn off the server and peer verification (TrustManager Concept).
		curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
		curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);
		curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
		
		if(!empty($download_file)){
			curl_setopt($ch, CURLOPT_FILE, $download_file);
		}
		
		// Get response from the server.
		$resp = curl_exec($ch);
		
		echo '<br />Resp: ';
		r_print($resp);
		echo '<br />Curl Error:';
		$curl_error = curl_error($ch);
		echo $curl_error;
		$errno = curl_errno($ch);
		r_print($errno);
		$error_message = curl_strerror($errno);
		r_print($error_message);
		
		$http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
		curl_close($ch);
		echo "HTTP_CODE: ".$http_code;
		
		$result = json_decode($resp, true);
		r_print($result);

		
		if(!empty($result['error']) && empty($ignore_errors)){
			if($result['error']['.tag'] == 'invalid_access_token'){
				$error[$result['error']['.tag']] = $l['invalid_access_token'];
			}elseif($result['error']['.tag'] == 'incorrect_offset'){
				$error[$result['error']['.tag']] = 'Incorrect Offset';
			}elseif($result['error'][$result['error']['.tag']]['.tag'] == 'insufficient_space'){
				$error[$result['error'][$result['error']['.tag']]['.tag']] = $l['insufficient_space'];
			}elseif(!empty($result['error'][$result['error']['.tag']]['.tag'])){
				$error[] = $result['error'][$result['error']['.tag']]['.tag'];
			}else{
				$error[$result['error']['.tag']] = $result['error']['.tag'];
			}
			
			return false;
		}
		
		return $result;
	}

function stream_write($data){
		global $error;
		
		if(!is_resource($this->wp)){
			$this->wp = fopen($this->tpfile, 'w+');
		}
		
		//Initially store the data in a memory
		fwrite($this->wp, $data);		
		$this->tmpsize += strlen($data);
		$data_size = strlen($data);
		
		// Are we already more than 4 MB ?
		if($this->tmpsize >= 4194304){
			
			rewind($this->wp);
			
			//Call upload append function to write the data from PHP Memory stream to Dropbox
			$this->upload_append($this->session_id, $this->wp, $this->tmpsize);
			
			// Close the temp file and reset the variables
			fclose($this->wp);
			$this->wp = NULL;
			$this->tmpsize = 0;
		}
		
		return $data_size;	
	}

// Dropbox API to upload
	function upload_append($session_id, $filep, $data_size){
		global $error;
		
		$args = json_encode(array('cursor' => array('session_id' => $session_id, 
											'offset' => $this->offset), 
								'close' => false));
		
		$upload_url = 'https://content.dropboxapi.com/2/files/upload_session/append_v2';
		$headers = array('Authorization: Bearer '.$this->access_token,
						'Dropbox-API-Arg: '.$args,
						'Content-Type: application/octet-stream');
		
		$resp = $this->__curl($upload_url, $headers, $filep, $data_size);
		
		if(is_null($resp)){
			$this->offset += $data_size;
			return $data_size;
		}
		
		return false;
		
	}

>>the steps to reproduce the issue, including relevant code snippet(s) and parameter value(s), but don't include any access or refresh token(s)

I guess the issue can be reproduced by uploading a file large in chunks of 4MB which could take more than 4hrs to complete

I have previously opened a ticket, in which you can find the error I'm receiving, below is the ticket id for the same:

Ticket #17124496

Awaiting your response.