cURL error 61 generally occurs due to issues in the gzip stream that prevents the uncompression of the full contents.

As a part of our Server Management Services, we help our Customers to fix SQL related errors regularly.

Let us today discuss the possible causes and fixes for this error.

What is cURL error 61?

cURL command helps in data transfer from or to servers. At times, users face the error code 61 while performing this transfer. A typical error message looks like:

cURL error 61: Unrecognized content encoding type. libcurl understands deflate, gzip content encodings.

This generally happens due to the following reasons:

1. Compression is enabled.
2. Plugin settings.
3. Content encoding.
4. Version of cURL

How to fix cURL error 61?

Let us now look at the possible reasons to fix this error.

The 61 error code commonly triggers on enabling compression in the server configuration. If compression is enabled in the server configuration, both Nginx and Apache add Transfer-Encoding: chunked to the response, and ranges are not supported.  Thus the solution here would be to request the files without compression. We could pass the –no-compress flag along with curl command.

Some of the plugins used in the site, particularly cache-related may have some compression settings turned on. This could trigger the cURL error. For instance, if the Gzip compression option enabled in W3 Total Cache,it can trigger this error. The fix here would be to disable the gzip compression from the plugin settings.

If the content encoding at the server end is something other than gzip or deflate, it may also trigger the 61 error code. This could also happen when gzip is disabled for the site. We need to cross-check the encoding at the server end.

The reason for this error might also be that the CURLOPT_ACCEPT_ENCODING is being set incorrectly or that the server is bad and ignoring the list of acceptable encodings. The solution here would be to compile your libcurl with the –with-brotli option.

Another common reason for this error is a lower version of cURL. An upgrade of the version of the cURL will help to fix the issue here.
 

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Conclusion

In short, cURL error 61 generally occurs due to issues in the gzip stream that prevents the uncompression of the full contents. Today, we saw how our Support Engineers fix this error.