Occassional Gateway Errors in Workflow

💬 Workflows
1
  1. My goal:Run Workflow that uploads data to mySQL server
  2. Issue: Occasionally, the workflow will have errors whilst running a code segment or getting data from SQL, reading "<html> <head><title>502 Bad Gateway</title></head> <body> <center><h1>502 Bad Gateway</h1></center> <hr><center>nginx</center> </body> </html>." Also, specifically in the code segments, occasionally a nonetype error will occur, and this occur because the loop that is getting data will return a similar error as the one listed above, but it lists out more information that I can not see as follows:
Error evaluating get_worksheets_loop (iteration 1): Error fetching data for get_worksheets_loop
 response: <html>
<head><title>502 Bad Gateway</title></head>
<body>
<center><h1>502 Bad Gateway</h1></center>
<hr><center>nginx</center>
</body>
</html>

 error: Unexpected token '<', "<html>
<h"... is not valid JSON
  1. Steps I've taken to troubleshoot: Looked at the logs and confirmed that they are not from our server that the workflow is touching
  2. Additional info: We are on Retool cloud. The specific data is sensitive, so if it is needed, I am willing to share problematic and the normal cases privately.
3

HI @Daniel_Fleuranvil,

This is a a pretty common issue when working with external resources inside Retool Workflows — especially when looping or making repeated SQL/API calls.
What sort of error handling do you have in place?

On the bottom of each block you have some basic settings. This should help.

chrome_H4NrjLHqtP
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You can also add basic retry handling like:

let attempt = 0;
let result = null;

while (attempt < 3) {
  try {
    result = await get_data_from_sql.trigger();
    if (result) break;
  } catch (err) {
    attempt++;
    await new Promise(r => setTimeout(r, 1000 * attempt)); // Exponential backoff
  }
}

return result;

Let me know if this helps and we can go from there.