What to do when Mergado cannot download the input feed#

When Mergado cannot download your input feed, the project is not regenerated and the output keeps older data. In most cases, the cause is not in Mergado. The server hosting your feed either rejects the download request or does not respond to it. This article helps you find out what is going on and points you to a solution — ideally so you can identify the cause yourself without waiting for a reply from support.

The steps apply to the project’s input feed as well as to files downloaded by the Data file import rule.

How to find out exactly what happened#

Do not rely on a general sense that “the project is not working”. Mergado records every attempt to download the feed:

In Mergado, open the project where the problem occurred.
Go to the History page.
In the Event type column, filter by Product import, or by Scheduled product import if the project regenerates automatically.

You will see the number of failed attempts and the related message. For the most common errors (401, 403, 404, 500, 502, 503 and 504), the message is specific and tells you right away what happened — in that case, continue with the table below. If you see only the generic “Unknown error” message, go straight to the section What “Unknown error” means.

What each error means#

Message in History	What is happening	Where to look for a solution
Access to the remote file was denied (401 Unauthorized).	The feed is protected by a username and password, and Mergado either does not have them or has incorrect ones.	Check the login credentials in the feed URL or in the Mergado Drive extension. If you changed them on the server, update them in Mergado as well.
The remote server refused to respond (403 Forbidden).	The server sees Mergado but denies it access. This is the most common case. The cause is usually an IP address whitelist, a WAF (a web firewall that filters traffic to your website), Cloudflare, or blocking of automated downloads.	Allow Mergado’s IP addresses. If you use Cloudflare, follow this guide.
The remote file does not exist (404 Not Found). No data was found at the specified URL.	There is no file at the specified URL. The feed was moved or renamed, or the URL contains a typo.	Open the feed URL in your browser. If you cannot find it either, get the current URL from your online store platform and correct it in the project settings.
An unspecified error occurred on the remote server (500 Internal Server Error).	The server hosting the feed ran into an internal error. Most often, generating the feed itself failed.	Try opening the URL in your browser. If the error persists, resolve it with your hosting provider or online store platform provider.
The remote server was unable to respond (502 Bad Gateway).	A server in front of your online store (a proxy or CDN) did not receive a valid response from the server that generates the feed.	This is usually a temporary outage. If the error persists, contact your hosting provider.
The remote server did not respond (503 Service Unavailable).	The server is overloaded, under maintenance, or temporarily unavailable.	Wait for the next download attempt. If the error keeps recurring, discuss server performance or scheduled maintenance with your hosting provider.
The remote server was unable to respond (504 Gateway Timeout).	Generating the feed took too long and the server did not manage to send a response in time.	Ask your hosting provider or online store platform provider to speed up feed generation, or to pre-generate the feed into a file.

A WAF (Web Application Firewall) is a security filter that inspects requests to your website and blocks suspicious ones. It is often part of your hosting or of services such as Cloudflare, and it sometimes blocks automated feed downloads by mistake.

What “Unknown error” means#

For other errors, History does not show a specific description, only the generic “Unknown error” message. This applies mainly to:

429 Too Many Requests — the server limits the number of requests and the feed download exceeded the limit.
Timeout — the server did not respond at all, or establishing the connection took too long.
Certificate / SSL error — the server has an invalid, expired or untrusted certificate.

In this case, you cannot tell the exact code and reason from History — only our technical support can see it. Before you contact them, try to verify the cause yourself — in most cases, you will find it without waiting for a reply:

Test the feed download the way Mergado sees it. Mergado does not download the feed through a browser. It downloads it automatically using the curl tool, identifying itself with the User-Agent MergadoBot. You can send the same request yourself. In a terminal (macOS, Linux, Windows 10 and later), run:
```
curl -I -A "MergadoBot" "https://your-feed-url"
```
- The first line of the response shows the HTTP code (for example, HTTP/2 200, 403, 429 or 503). It tells you the cause even when History shows only “Unknown error”.
- The response contains the cf-mitigated: challenge header → Cloudflare is blocking the feed. Follow the Cloudflare guide.
- The command returns nothing or finishes only after a long time → this corresponds to a timeout.
- The command ends with a certificate error → this is an SSL error. Ask your hosting provider to renew the certificate.
The test runs from your IP address, not from Mergado’s. If it returns 200 but Mergado still cannot download the feed, the server is most likely blocking Mergado’s IP address directly. Check this in the log (next step) or with your hosting provider.
Check your hosting’s own access/error log (in your hosting administration — unlike our History, it shows the actual HTTP status). Find the time of the failed attempt from History and look for requests from the IP address 81.31.39.112.
- The request is not there at all → it was stopped before it reached your application (firewall, WAF, network level) → this corresponds to a timeout.
- The request is there and you see a specific code (for example, 429) → you have the exact cause without waiting for us. For a 429 error, ask your server administrator or hosting provider to raise the limit for Mergado’s IP address.
Compare the time of the last successful entry with the first failed one in History. This helps you link the problem to a specific change — a new security rule, enabling Cloudflare, a hosting migration, or a certificate renewal.

If you still cannot find the cause, email us at mergado@mergado.cz — include a link to the project, the feed URL, and the time the problem occurred. Once you have gone through these checks, we will look up the code and exact reason for you in our administration.

Special case: it used to work and stopped without me changing anything#

This happens more often than you might think, and it is almost never an error on Mergado’s side. Typical causes:

Your hosting provider introduced new security rules. A real case: a large Czech hosting provider introduced a new rule for detecting suspicious traffic and mistakenly flagged Mergado’s traffic as risky. As a result, it blocked feed downloads for all online stores on its servers until we notified it.
You enabled Cloudflare or its settings changed.
The certificate expired.
You migrated your hosting or the server’s IP address changed, and the whitelist is no longer there.
The password or hash in the feed URL changed, for example after an online store update.

How to tell: in the project History, find the last successful download and compare it with the first failed one. The moment it broke is the most valuable piece of information for you and for your hosting provider.

What to do#

Test the feed the way Mergado downloads it — with the command curl -I -A "MergadoBot" "https://your-feed-url" (see the section What “Unknown error” means for details). Opening the feed in your browser is not enough: the browser may load the feed even when the server blocks automated downloads.
Check the project History to see which error keeps recurring. If it is a specific message (401, 403, 404, 500, 502, 503 or 504), find it in the table above. If it is “Unknown error”, follow the section What “Unknown error” means.
Check your IP address whitelist. Mergado downloads the input feed from the IP address 81.31.39.112. If you use extensions, add their IP addresses as well.
Make sure the feed is not protected in several ways at once. Combining a whitelist with a hash in the URL is a frequent source of problems, typically with Shoptet feeds.
If you use Cloudflare, set up an exception according to the separate guide. Adding the IP address to the whitelist is not enough there.
Contact your hosting provider if none of the above helped. Explain that this is a legitimate automated download of a product feed and ask them to unblock the IP address 81.31.39.112. Include the time when downloading stopped working.
Contact our support if you are not sure. Email mergado@mergado.cz and include a link to the project, the feed URL, and the time the problem occurred.

FAQ#

Does a download error mean I will lose data in the output?#

No. When a download fails, Mergado keeps the data from the last successful import — if there has been one. The output feed remains available, but it contains older information until the download succeeds again. If the feed has never been downloaded successfully (for example, in a newly created project), there is no data in the output yet.

Why does my feed fail to download when it works in the browser?#

Your browser and Mergado access the feed differently. Mergado downloads the feed automatically using the curl tool, identifying itself as MergadoBot. A browser can handle JavaScript and security challenges, while automated downloads cannot. The server may also distinguish access by IP address, and yours is different from Mergado’s. The most common causes are an IP address whitelist, a WAF, or Cloudflare. That is why a curl test, described in the section What “Unknown error” means, is more reliable than the browser.

Does the same apply to the Data file import rule?#

Yes. The Data file import rule downloads the file the same way as the input feed, so the causes and solutions are the same.

How can I tell if my hosting provider is blocking me?#

A reliable sign is a timeout error, where the server does not respond at all even though a curl test with the MergadoBot identification passes normally from your computer. If the problem also started overnight without any change on your part, blocking by your hosting provider is very likely. Contact their support.

Why does History show only “Unknown error” and not a specific code?#

History shows a specific description only for the most common errors (401, 403, 404, 500, 502, 503 and 504). Other errors, such as 429, a timeout or a certificate problem, appear generically as “Unknown error” — at that point, only our support can see the exact code. You can find out how to verify the cause yourself in the section What “Unknown error” means.

Do I need to do anything after fixing the problem to regenerate the project?#

Mergado tries to download the feed automatically with every subsequent regeneration. If you want to check the result right away, start the regeneration manually in the project.