Current situation does an error difficult to decrypt because the plugin doesn't check for the response status code:
2019-06-12 11:14:33.668+0000 [id=86689] SEVERE o.j.c.p.j.client.RestApiClient#getRemoteItems: Failed to list job from remote <url> org.xml.sax.SAXParseException; lineNumber: 10; columnNumber: 3; The element type "hr" must be terminated by the matching end-tag "</hr>". at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:257) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:339) at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:121) at org.jenkins.ci.plugins.jobimport.client.RestApiClient.getRemoteItems(RestApiClient.java:34) at org.jenkins.ci.plugins.jobimport.JobImportAction.doQueryInternal(JobImportAction.java:278) at org.jenkins.ci.plugins.jobimport.JobImportAction.doQuery(JobImportAction.java:174)
Proposed fix checking for this status code:
Jun 12, 2019 5:36:04 PM org.jenkins.ci.plugins.jobimport.client.RestApiClient getRemoteItems
SEVERE: Failed to list job from remote <url>/SEVERE: Failed to list job from remote <url>/org.acegisecurity.AccessDeniedException: Remote Jenkins denied access. Please check the provided credentials at org.jenkins.ci.plugins.jobimport.utils.URLUtils.fetchUrl(URLUtils.java:88) at org.jenkins.ci.plugins.jobimport.client.RestApiClient.getRemoteItems(RestApiClient.java:35) at org.jenkins.ci.plugins.jobimport.JobImportAction.doQueryInternal(JobImportAction.java:278) at org.jenkins.ci.plugins.jobimport.JobImportAction.doQuery(JobImportAction.java:174)