When the bot receives a 502 error, it's reported to be a Server Hangup, when it doesn't the response size of the server is 0 bytes, empty.
Here are a bunch of requests that failed from the failure log.
Date/Time: Tue, 26 Jan 2021 14:21:34 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => revisions [titles] => Wikipedia:Requests for adminship [rvprop] => timestamp|ids|user|comment|content [rawcontinue] => 1 [rvdir] => older [rvlimit] => 1 [format] => php [servedby] => [requestid] => 756061289 ) Raw Data: <!DOCTYPE html> <html lang="en"> <meta charset="utf-8"> <title>Wikimedia Error</title> <style> * { margin: 0; padding: 0; } body { background: #fff; font: 15px/1.6 sans-serif; color: #333; } .content { margin: 7% auto 0; padding: 2em 1em 1em; max-width: 640px; } .footer { clear: both; margin-top: 14%; border-top: 1px solid #e5e5e5; background: #f9f9f9; padding: 2em 0; font-size: 0.8em; text-align: center; } img { float: left; margin: 0 2em 2em 0; } a img { border: 0; } h1 { margin-top: 1em; font-size: 1.2em; } .content-text { overflow: hidden; overflow-wrap: break-word; word-wrap: break-word; -webkit-hyphens: auto; -moz-hyphens: auto; -ms-hyphens: auto; hyphens: auto; } p { margin: 0.7em 0 1em 0; } a { color: #0645ad; text-decoration: none; } a:hover { text-decoration: underline; } code { font-family: sans-serif; } .text-muted { color: #777; } </style> <div class="content" role="main"> <a href="https://www.wikimedia.org"><img src="https://www.wikimedia.org/static/images/wmf-logo.png" srcset="https://www.wikimedia.org/static/images/wmf-logo-2x.png 2x" alt="Wikimedia" width="135" height="101"> </a> <h1>Error</h1> <div class="content-text"> <p>Our servers are currently under maintenance or experiencing a technical problem. Please <a href="" title="Reload this page" onclick="window.location.reload(false); return false">try again</a> in a few minutes.</p> <p>See the error message at the bottom of this page for more information.</p> </div> </div> <div class="footer"><p>If you report this error to the Wikimedia System Administrators, please include the details below.</p><p class='text-muted'><code>Request from 172.16.2.21 via cp1089.eqiad.wmnet, ATS/8.0.8<br>Error: 502, Server Hangup at 2021-01-26 14:21:34 GMT</code></p></div> </html> UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:21:34 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => revisions [titles] => List of Foster's Home for Imaginary Friends episodes [rvprop] => timestamp|ids|user|comment|content [rawcontinue] => 1 [rvdir] => older [rvlimit] => 1 [format] => php [servedby] => [requestid] => 1867423561 ) Raw Data: <!DOCTYPE html> <html lang="en"> <meta charset="utf-8"> <title>Wikimedia Error</title> <style> * { margin: 0; padding: 0; } body { background: #fff; font: 15px/1.6 sans-serif; color: #333; } .content { margin: 7% auto 0; padding: 2em 1em 1em; max-width: 640px; } .footer { clear: both; margin-top: 14%; border-top: 1px solid #e5e5e5; background: #f9f9f9; padding: 2em 0; font-size: 0.8em; text-align: center; } img { float: left; margin: 0 2em 2em 0; } a img { border: 0; } h1 { margin-top: 1em; font-size: 1.2em; } .content-text { overflow: hidden; overflow-wrap: break-word; word-wrap: break-word; -webkit-hyphens: auto; -moz-hyphens: auto; -ms-hyphens: auto; hyphens: auto; } p { margin: 0.7em 0 1em 0; } a { color: #0645ad; text-decoration: none; } a:hover { text-decoration: underline; } code { font-family: sans-serif; } .text-muted { color: #777; } </style> <div class="content" role="main"> <a href="https://www.wikimedia.org"><img src="https://www.wikimedia.org/static/images/wmf-logo.png" srcset="https://www.wikimedia.org/static/images/wmf-logo-2x.png 2x" alt="Wikimedia" width="135" height="101"> </a> <h1>Error</h1> <div class="content-text"> <p>Our servers are currently under maintenance or experiencing a technical problem. Please <a href="" title="Reload this page" onclick="window.location.reload(false); return false">try again</a> in a few minutes.</p> <p>See the error message at the bottom of this page for more information.</p> </div> </div> <div class="footer"><p>If you report this error to the Wikimedia System Administrators, please include the details below.</p><p class='text-muted'><code>Request from 172.16.2.21 via cp1087.eqiad.wmnet, ATS/8.0.8<br>Error: 502, Server Hangup at 2021-01-26 14:21:34 GMT</code></p></div> </html> UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:21:34 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => revisions [titles] => List of Foster's Home for Imaginary Friends episodes [rvprop] => timestamp|ids|user|comment|content [rawcontinue] => 1 [rvdir] => older [rvlimit] => 1 [format] => php [servedby] => [requestid] => 1867423561 ) Raw Data: <!DOCTYPE html> <html lang="en"> <meta charset="utf-8"> <title>Wikimedia Error</title> <style> * { margin: 0; padding: 0; } body { background: #fff; font: 15px/1.6 sans-serif; color: #333; } .content { margin: 7% auto 0; padding: 2em 1em 1em; max-width: 640px; } .footer { clear: both; margin-top: 14%; border-top: 1px solid #e5e5e5; background: #f9f9f9; padding: 2em 0; font-size: 0.8em; text-align: center; } img { float: left; margin: 0 2em 2em 0; } a img { border: 0; } h1 { margin-top: 1em; font-size: 1.2em; } .content-text { overflow: hidden; overflow-wrap: break-word; word-wrap: break-word; -webkit-hyphens: auto; -moz-hyphens: auto; -ms-hyphens: auto; hyphens: auto; } p { margin: 0.7em 0 1em 0; } a { color: #0645ad; text-decoration: none; } a:hover { text-decoration: underline; } code { font-family: sans-serif; } .text-muted { color: #777; } </style> <div class="content" role="main"> <a href="https://www.wikimedia.org"><img src="https://www.wikimedia.org/static/images/wmf-logo.png" srcset="https://www.wikimedia.org/static/images/wmf-logo-2x.png 2x" alt="Wikimedia" width="135" height="101"> </a> <h1>Error</h1> <div class="content-text"> <p>Our servers are currently under maintenance or experiencing a technical problem. Please <a href="" title="Reload this page" onclick="window.location.reload(false); return false">try again</a> in a few minutes.</p> <p>See the error message at the bottom of this page for more information.</p> </div> </div> <div class="footer"><p>If you report this error to the Wikimedia System Administrators, please include the details below.</p><p class='text-muted'><code>Request from 172.16.2.21 via cp1087.eqiad.wmnet, ATS/8.0.8<br>Error: 502, Server Hangup at 2021-01-26 14:21:34 GMT</code></p></div> </html> UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:21:34 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => revisions [titles] => List of Foster's Home for Imaginary Friends episodes [rvprop] => timestamp|ids|user|comment|content [rawcontinue] => 1 [rvdir] => older [rvlimit] => 1 [format] => php [servedby] => [requestid] => 1867423561 ) Raw Data: <!DOCTYPE html> <html lang="en"> <meta charset="utf-8"> <title>Wikimedia Error</title> <style> * { margin: 0; padding: 0; } body { background: #fff; font: 15px/1.6 sans-serif; color: #333; } .content { margin: 7% auto 0; padding: 2em 1em 1em; max-width: 640px; } .footer { clear: both; margin-top: 14%; border-top: 1px solid #e5e5e5; background: #f9f9f9; padding: 2em 0; font-size: 0.8em; text-align: center; } img { float: left; margin: 0 2em 2em 0; } a img { border: 0; } h1 { margin-top: 1em; font-size: 1.2em; } .content-text { overflow: hidden; overflow-wrap: break-word; word-wrap: break-word; -webkit-hyphens: auto; -moz-hyphens: auto; -ms-hyphens: auto; hyphens: auto; } p { margin: 0.7em 0 1em 0; } a { color: #0645ad; text-decoration: none; } a:hover { text-decoration: underline; } code { font-family: sans-serif; } .text-muted { color: #777; } </style> <div class="content" role="main"> <a href="https://www.wikimedia.org"><img src="https://www.wikimedia.org/static/images/wmf-logo.png" srcset="https://www.wikimedia.org/static/images/wmf-logo-2x.png 2x" alt="Wikimedia" width="135" height="101"> </a> <h1>Error</h1> <div class="content-text"> <p>Our servers are currently under maintenance or experiencing a technical problem. Please <a href="" title="Reload this page" onclick="window.location.reload(false); return false">try again</a> in a few minutes.</p> <p>See the error message at the bottom of this page for more information.</p> </div> </div> <div class="footer"><p>If you report this error to the Wikimedia System Administrators, please include the details below.</p><p class='text-muted'><code>Request from 172.16.2.21 via cp1087.eqiad.wmnet, ATS/8.0.8<br>Error: 502, Server Hangup at 2021-01-26 14:21:34 GMT</code></p></div> </html> UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:21:34 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => info [inprop] => protection|talkid|watched|watchers|notificationtimestamp|subjectid|url|readable|preload|displaytitle [titles] => User:Cyberbot I/Run/Meta-cont [redirects] => [format] => php [servedby] => [requestid] => 554762138 ) Raw Data: <!DOCTYPE html> <html lang="en"> <meta charset="utf-8"> <title>Wikimedia Error</title> <style> * { margin: 0; padding: 0; } body { background: #fff; font: 15px/1.6 sans-serif; color: #333; } .content { margin: 7% auto 0; padding: 2em 1em 1em; max-width: 640px; } .footer { clear: both; margin-top: 14%; border-top: 1px solid #e5e5e5; background: #f9f9f9; padding: 2em 0; font-size: 0.8em; text-align: center; } img { float: left; margin: 0 2em 2em 0; } a img { border: 0; } h1 { margin-top: 1em; font-size: 1.2em; } .content-text { overflow: hidden; overflow-wrap: break-word; word-wrap: break-word; -webkit-hyphens: auto; -moz-hyphens: auto; -ms-hyphens: auto; hyphens: auto; } p { margin: 0.7em 0 1em 0; } a { color: #0645ad; text-decoration: none; } a:hover { text-decoration: underline; } code { font-family: sans-serif; } .text-muted { color: #777; } </style> <div class="content" role="main"> <a href="https://www.wikimedia.org"><img src="https://www.wikimedia.org/static/images/wmf-logo.png" srcset="https://www.wikimedia.org/static/images/wmf-logo-2x.png 2x" alt="Wikimedia" width="135" height="101"> </a> <h1>Error</h1> <div class="content-text"> <p>Our servers are currently under maintenance or experiencing a technical problem. Please <a href="" title="Reload this page" onclick="window.location.reload(false); return false">try again</a> in a few minutes.</p> <p>See the error message at the bottom of this page for more information.</p> </div> </div> <div class="footer"><p>If you report this error to the Wikimedia System Administrators, please include the details below.</p><p class='text-muted'><code>Request from 172.16.2.21 via cp1087.eqiad.wmnet, ATS/8.0.8<br>Error: 502, Server Hangup at 2021-01-26 14:21:34 GMT</code></p></div> </html> UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:21:35 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => info [inprop] => protection|talkid|watched|watchers|notificationtimestamp|subjectid|url|readable|preload|displaytitle [titles] => Wikipedia:Changing username/Usurpations [redirects] => [format] => php [servedby] => [requestid] => 182313283 ) Raw Data: <!DOCTYPE html> <html lang="en"> <meta charset="utf-8"> <title>Wikimedia Error</title> <style> * { margin: 0; padding: 0; } body { background: #fff; font: 15px/1.6 sans-serif; color: #333; } .content { margin: 7% auto 0; padding: 2em 1em 1em; max-width: 640px; } .footer { clear: both; margin-top: 14%; border-top: 1px solid #e5e5e5; background: #f9f9f9; padding: 2em 0; font-size: 0.8em; text-align: center; } img { float: left; margin: 0 2em 2em 0; } a img { border: 0; } h1 { margin-top: 1em; font-size: 1.2em; } .content-text { overflow: hidden; overflow-wrap: break-word; word-wrap: break-word; -webkit-hyphens: auto; -moz-hyphens: auto; -ms-hyphens: auto; hyphens: auto; } p { margin: 0.7em 0 1em 0; } a { color: #0645ad; text-decoration: none; } a:hover { text-decoration: underline; } code { font-family: sans-serif; } .text-muted { color: #777; } </style> <div class="content" role="main"> <a href="https://www.wikimedia.org"><img src="https://www.wikimedia.org/static/images/wmf-logo.png" srcset="https://www.wikimedia.org/static/images/wmf-logo-2x.png 2x" alt="Wikimedia" width="135" height="101"> </a> <h1>Error</h1> <div class="content-text"> <p>Our servers are currently under maintenance or experiencing a technical problem. Please <a href="" title="Reload this page" onclick="window.location.reload(false); return false">try again</a> in a few minutes.</p> <p>See the error message at the bottom of this page for more information.</p> </div> </div> <div class="footer"><p>If you report this error to the Wikimedia System Administrators, please include the details below.</p><p class='text-muted'><code>Request from 172.16.2.21 via cp1075.eqiad.wmnet, ATS/8.0.8<br>Error: 502, Server Hangup at 2021-01-26 14:21:35 GMT</code></p></div> </html> UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:21:35 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => revisions [titles] => Wikipedia:Requests for adminship [rvprop] => timestamp|ids|user|comment|content [rawcontinue] => 1 [rvdir] => older [rvlimit] => 1 [format] => php [servedby] => [requestid] => 1317230359 ) Raw Data: <!DOCTYPE html> <html lang="en"> <meta charset="utf-8"> <title>Wikimedia Error</title> <style> * { margin: 0; padding: 0; } body { background: #fff; font: 15px/1.6 sans-serif; color: #333; } .content { margin: 7% auto 0; padding: 2em 1em 1em; max-width: 640px; } .footer { clear: both; margin-top: 14%; border-top: 1px solid #e5e5e5; background: #f9f9f9; padding: 2em 0; font-size: 0.8em; text-align: center; } img { float: left; margin: 0 2em 2em 0; } a img { border: 0; } h1 { margin-top: 1em; font-size: 1.2em; } .content-text { overflow: hidden; overflow-wrap: break-word; word-wrap: break-word; -webkit-hyphens: auto; -moz-hyphens: auto; -ms-hyphens: auto; hyphens: auto; } p { margin: 0.7em 0 1em 0; } a { color: #0645ad; text-decoration: none; } a:hover { text-decoration: underline; } code { font-family: sans-serif; } .text-muted { color: #777; } </style> <div class="content" role="main"> <a href="https://www.wikimedia.org"><img src="https://www.wikimedia.org/static/images/wmf-logo.png" srcset="https://www.wikimedia.org/static/images/wmf-logo-2x.png 2x" alt="Wikimedia" width="135" height="101"> </a> <h1>Error</h1> <div class="content-text"> <p>Our servers are currently under maintenance or experiencing a technical problem. Please <a href="" title="Reload this page" onclick="window.location.reload(false); return false">try again</a> in a few minutes.</p> <p>See the error message at the bottom of this page for more information.</p> </div> </div> <div class="footer"><p>If you report this error to the Wikimedia System Administrators, please include the details below.</p><p class='text-muted'><code>Request from 172.16.2.21 via cp1085.eqiad.wmnet, ATS/8.0.8<br>Error: 502, Server Hangup at 2021-01-26 14:21:35 GMT</code></p></div> </html> UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:52:19 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => info [inprop] => protection|talkid|watched|watchers|notificationtimestamp|subjectid|url|readable|preload|displaytitle [titles] => Wikipedia:Requests for adminship [redirects] => [format] => php [servedby] => [requestid] => 723665756 ) Raw Data: UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:52:19 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => info [inprop] => protection|talkid|watched|watchers|notificationtimestamp|subjectid|url|readable|preload|displaytitle [titles] => Wikipedia:Articles for deletion/List of international cricket five-wicket hauls by Craig McDermott [redirects] => [format] => php [servedby] => [requestid] => 137476619 ) Raw Data: UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:52:20 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => info [inprop] => protection|talkid|watched|watchers|notificationtimestamp|subjectid|url|readable|preload|displaytitle [titles] => New Hope Club [format] => php [servedby] => [requestid] => 574193863 ) Raw Data: UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:52:20 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => revisions [titles] => Wikipedia:Changing username/Simple [rvprop] => timestamp|ids|user|comment|content [rawcontinue] => 1 [rvdir] => older [rvlimit] => 1 [format] => php [servedby] => [requestid] => 533125398 ) Raw Data: UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:52:20 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => info [inprop] => protection|talkid|watched|watchers|notificationtimestamp|subjectid|url|readable|preload|displaytitle [titles] => User:Cyberbot I/Run/Adminstatscy [redirects] => [format] => php [servedby] => [requestid] => 141685735 ) Raw Data: UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:52:20 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => revisions [titles] => Wikipedia:Requests for adminship/Ronjohn [rvprop] => timestamp|ids|user|comment|content [rawcontinue] => 1 [rvdir] => older [rvlimit] => 1 [format] => php [servedby] => [requestid] => 185024011 ) Raw Data: UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:52:20 0000 Method: GET URL: https://simple.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => info [inprop] => protection|talkid|watched|watchers|notificationtimestamp|subjectid|url|readable|preload|displaytitle [titles] => Ivan Turgenev [redirects] => [format] => php [servedby] => [requestid] => 770007772 ) Raw Data: UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:52:23 0000 Method: GET URL: https://commons.wikimedia.org/w/api.php Parameters: Array ( [list] => allusers [auprop] => blockinfo|groups|editcount|registration [_limit] => [augroup] => sysop [action] => query [aulimit] => max [rawcontinue] => 1 [format] => php [servedby] => [requestid] => 452204742 ) Raw Data: UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 14:52:29 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => info [inprop] => protection|talkid|watched|watchers|notificationtimestamp|subjectid|url|readable|preload|displaytitle [titles] => Wikipedia:Articles for deletion/List of international cricket five-wicket hauls by Craig McDermott [redirects] => [format] => php [servedby] => [requestid] => 137476619 ) Raw Data: UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 15:13:41 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [list] => allusers [auprop] => blockinfo|groups|editcount|registration [_limit] => [augroup] => sysop [action] => query [aulimit] => max [rawcontinue] => 1 [format] => php [servedby] => [requestid] => 1010401488 ) Raw Data: UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 15:18:22 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => revisions [titles] => Mary I of England [rvprop] => timestamp|ids|user|comment|content [rawcontinue] => 1 [rvdir] => older [rvlimit] => 1 [format] => php [servedby] => [requestid] => 947306989 ) Raw Data: UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 16:14:27 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [list] => allusers [auprop] => blockinfo|groups|editcount|registration [_limit] => [augroup] => sysop [action] => query [aulimit] => max [rawcontinue] => 1 [format] => php [servedby] => [requestid] => 1868822084 ) Raw Data: UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 16:40:38 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [action] => query [prop] => revisions [titles] => America's Next Top Model (season 22) [rvprop] => timestamp|ids|user|comment|content [rawcontinue] => 1 [rvdir] => older [rvlimit] => 1 [format] => php [servedby] => [requestid] => 614076390 ) Raw Data: UNSERIALIZATION FAILED Date/Time: Tue, 26 Jan 2021 18:00:08 0000 Method: GET URL: https://en.wikipedia.org/w/api.php Parameters: Array ( [list] => allusers [auprop] => blockinfo|groups|editcount|registration [_limit] => [augroup] => sysop [action] => query [aulimit] => max [rawcontinue] => 1 [format] => php [servedby] => [requestid] => 832551312 ) Raw Data: UNSERIALIZATION FAILED