Team City - URL Trigger - Not working - teamcity

Question

We are using TeamCity Professional 9.1.7, We have setup automated tests in Team City which using Selenium.
In order to invoke the test suite we are leveraging the URL build trigger.
Once the application is deployed on the target server we have an URL which will return the installed version and date time stamp on the server everyday.
When we made an attempt to hit URL manually the version and date time is getting returned. And there is connectivity between TeamCity and deployed server.
We have configured the URL as : abc.XXX/sample.txt and TeamCity is complaining with the following message:
URL build trigger failed with error: URL abc.XXX/sample.txt: null
Hide stacktrace
jetbrains.buildServer.buildTriggers.BuildTriggerException: URL build trigger failed with error: URL https://abc.XXX/sample.txt: null
at jetbrains.buildServer.buildTriggers.url.UrlBuildTrigger$2.makeTriggerException(UrlBuildTrigger.java:117)
at jetbrains.buildServer.buildTriggers.async.impl.AsyncPolledBuildTrigger.processJobResults(AsyncPolledBuildTrigger.java:146)
at jetbrains.buildServer.buildTriggers.async.impl.AsyncPolledBuildTrigger.triggerBuild(AsyncPolledBuildTrigger.java:60)
at jetbrains.buildServer.serverSide.impl.BuildTriggersChecker$4.run(BuildTriggersChecker.java)
at jetbrains.buildServer.util.NamedThreadFactory.executeWithNewThreadName(NamedThreadFactory.java:89)
at jetbrains.buildServer.serverSide.impl.BuildTriggersChecker.callTrigger(BuildTriggersChecker.java:32)
at jetbrains.buildServer.serverSide.impl.BuildTriggersChecker.access$1100(BuildTriggersChecker.java:65)
at jetbrains.buildServer.serverSide.impl.BuildTriggersChecker$BuildTriggersGroup.processTriggers(BuildTriggersChecker.java:37)
at jetbrains.buildServer.serverSide.impl.BuildTriggersChecker.triggerBuilds(BuildTriggersChecker.java:50)
at jetbrains.buildServer.serverSide.impl.BuildServerRunner$4.doSomething(BuildServerRunner.java)
at jetbrains.buildServer.serverSide.impl.BuildServerRunner$BuildServerWorker.runAction(BuildServerRunner.java:47)
at jetbrains.buildServer.serverSide.impl.BuildServerRunner$BuildServerWorker.run(BuildServerRunner.java:9)
at java.lang.Thread.run(Thread.java:745)
Caused by: jetbrains.buildServer.buildTriggers.async.DetectionException: URL https://abc.XXX/sample.txt: null
at jetbrains.buildServer.buildTriggers.url.UrlBuildTrigger.createThrowableResult(UrlBuildTrigger.java:203)
at jetbrains.buildServer.buildTriggers.url.UrlBuildTrigger.access$700(UrlBuildTrigger.java:39)
at jetbrains.buildServer.buildTriggers.url.UrlBuildTrigger$2$1.perform(UrlBuildTrigger.java:169)
at jetbrains.buildServer.buildTriggers.async.impl.AsyncPolledBuildTrigger$2.run(AsyncPolledBuildTrigger.java:172)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
... 1 more
Caused by: jetbrains.buildServer.buildTriggers.url.ResourceHashProviderException: URL https://abc.XXX/sample.txt: null
at jetbrains.buildServer.buildTriggers.url.HttpResourceHashProvider.getResourceHash(HttpResourceHashProvider.java:115)
at jetbrains.buildServer.buildTriggers.url.UrlBuildTrigger$2$1.perform(UrlBuildTrigger.java:149)
... 4 more
Caused by: java.lang.NullPointerException
Please help.

Answer 1

Finally the issue resolved, our URL was having underscore _ in it. There seems to be a constraint/defect with team city that the URL trigger cant have underscore _ in it.
We replaced all _ with - and it worked.