Troubleshooting of curl errors

cUrl "is used in command lines or scripts to transfer data."[1] (alternative library to achive sampe purpose: (1) PHP naive Client URL Library (2) cURL class for PHP (3) Installing cURL on Cygwin on Windows)

How to debut the cUrl command: (1) Enable the verbose option e.g. "... run the command with the -v / --verbose option to get more information." or (2) Enable the trace options e.g. --trace-ascii [filename] Note: trace options will be override by verbose option if enable both options.

How to resolve cUrl error (#5): Unsupported proxy syntax

Condition: the username of socks5 proxy contains @ symbol such as [email protected]

curl_setopt($ch, CURLOPT_PROXY, 'socks5://username:password@localhost:12345');
// result is ok

curl_setopt($ch, CURLOPT_PROXY, 'socks5://[email protected]:password@localhost:12345');
// met cUrl error (#5): Unsupported proxy syntax

Solution: Escape the special symbol using URL Encode and Decode - Online or urlencode function

curl_setopt($ch, CURLOPT_PROXY, 'socks5://bob%40email.com:password@localhost:12345');
// result is ok

How to resolve cUrl error (#56): OpenSSL SSL_read: No error.

Condition: The curl vesion 7.67.0 on windows met problem. Result of curl_version returned:

version: Array
(
    [version_number] => 475904
    [age] => 5
    [features] => 2953117
    [ssl_version_number] => 0
    [version] => 7.67.0
    [host] => x86_64-pc-win32
    [ssl_version] => OpenSSL/1.1.1d
    [libz_version] => 1.2.11
)

Solution: Use other version of curl command or curl on Cygwin or cURL class for PHP.

Related articles

• cURL error 56: OpenSSL SSL_read: No error information · Issue #4982 · curl/curl

How to resolve Error 405 Method Not Allowed

When I tried to crawl the web resource but met the error message: "Error 405 Method Not Allowed"

Solution: Make sure using the correct HTTP request method e.g. GET or POST to access the web resource.

How to resolve Error 415 Unsupported Media Type

When I tried to POST JSON (as payload) but met the error message: "Error 415 Unsupported Media Type"

Solution: Set the cUrl with the header Content-Type: application/json Example syntax of cUrl command as following:

curl -X POST --header "Content-Type: application/json" --data '{"user" : "your_user_name", "token" : "your_token"}' "https://example.com/"

How to rseolve cURL returns binary data instead of html or json

• php - cURL returns binary data instead of html - Stack Overflow
• 解決 cUrl 下載的網頁或 JSON 看起來像是亂碼的問題

How to resolve the downloaded file was empty

Error condition

• When I executed the Curl command curl -O https://path/to/plain_text.txt, but the downloaded file was empty.

Solution

• After I enabled verbose option, I found the HTTP status code HTTP/1.1 302 Moved Temporarily. I added the location (-L) parameter to resolve the downloaded file was empty: curl -L -O https://path/to/plain_text.txt,

The truncated result after executed the command: curl -v -O https://path/to/plain_text.txt

< HTTP/1.1 302 Moved Temporarily
< Server: nginx
< Date: Tue, 25 Aug 2020 03:45:13 GMT
< Content-Type: text/html
< Transfer-Encoding: chunked
< Connection: keep-alive
< Keep-Alive: timeout=60
< Location: /path/to/plain_text.txt

How to resolve the error: no matches found

Error condition

• When I executed the Curl command curl http://website.test/http_status.php?case=500, but I met the error message: "zsh: no matches found: http://website.test/http_status.php?case=500"

Solution

• Double quote the URL e.g. curl "http://website.test/http_status.php?case=500"

How to resolve the error: zsh: parse error near `&'

Error condition

% curl -XPOST http://localhost:3000/ -H "Content-Type: application/json"  -d'{"url": "https://someweb.com/Today's_Biggest_Trends"}'
dquote>

Solution: Escape the single quote ' became '' (repeat the single quote twice)

% curl -XPOST http://localhost:3000/ -H "Content-Type: application/json"  -d'{"url": "https://someweb.com/Today''s_Biggest_Trends"}'

Trivial Solution NOT WORK: single quote ' became \'

% curl -XPOST http://localhost:3000/ -H "Content-Type: application/json"  -d'{"url": "https://someweb.com/Today\'s_Biggest_Trends"}'
dquote>

Further reading

• Introduction - Everything curl
• curl - How To Use
• bash - CURL escape single quote - Stack Overflow

References

Troubleshooting of ...

• Troubleshooting of Excel errors

• PHP, cUrl, Python, selenium, HTTP status code errors

• Database: SQL syntax debug, MySQL errors, MySQLTuner errors or PostgreSQL errors

• Troubleshooting of regular expression

• HTML/Javascript: Troubleshooting of javascript, XPath

• Software: Mediawiki, Docker, FTP problems, online conference software

• Test connectivity for the web service, Web Ping, Network problem, Web user behavior, Web scrape troubleshooting

Template

• Bug report template