can't open customizer menu. it says "connecting to spigotmc"

[18:01:30 INFO]: xXMarcinatorXx issued server command: /customizer
[18:01:31 WARN]: [UltraCustomizer] Plugin UltraCustomizer v1.2.4 generated an exception while executing task 441
java.lang.NoSuchMethodError: org.apache.http.conn.ssl.SSLConnectionSocketFactory.<init>(Ljavax/net/ssl/SSLContext;[Ljava/lang/String;[Ljava/lang/String;Ljavax/net/ssl/HostnameVerifier;)V
        at com.gargoylesoftware.htmlunit.httpclient.HtmlUnitSSLConnectionSocketFactory.<init>(HtmlUnitSSLConnectionSocketFactory.java:133) ~[?:?]
        at com.gargoylesoftware.htmlunit.httpclient.HtmlUnitSSLConnectionSocketFactory.buildSSLSocketFactory(HtmlUnitSSLConnectionSocketFactory.java:99) ~[?:?]
        at com.gargoylesoftware.htmlunit.HttpWebConnection.configureHttpsScheme(HttpWebConnection.java:637) ~[?:?]
        at com.gargoylesoftware.htmlunit.HttpWebConnection.createHttpClient(HttpWebConnection.java:569) ~[?:?]
        at com.gargoylesoftware.htmlunit.HttpWebConnection.getHttpClientBuilder(HttpWebConnection.java:531) ~[?:?]
        at com.gargoylesoftware.htmlunit.HttpWebConnection.getResponse(HttpWebConnection.java:173) ~[?:?]
        at com.gargoylesoftware.htmlunit.WebClient.loadWebResponseFromWebConnection(WebClient.java:1364) ~[?:?]
        at com.gargoylesoftware.htmlunit.WebClient.loadWebResponse(WebClient.java:1281) ~[?:?]
        at com.gargoylesoftware.htmlunit.WebClient.getPage(WebClient.java:383) ~[?:?]
        at com.gargoylesoftware.htmlunit.WebClient.getPage(WebClient.java:305) ~[?:?]
        at com.gargoylesoftware.htmlunit.WebClient.getPage(WebClient.java:469) ~[?:?]
        at me.TechsCode.UltraCustomizer.base.update.VirtualBrowser.request(VirtualBrowser.java:43) ~[?:?]
        at me.TechsCode.UltraCustomizer.base.update.SpigotMC.checkIfLoggedIn(SpigotMC.java:131) ~[?:?]
        at me.TechsCode.UltraCustomizer.base.update.SpigotMC.<init>(SpigotMC.java:58) ~[?:?]
        at me.TechsCode.UltraCustomizer.base.update.UpdateChecker.lambda$new$0(UpdateChecker.java:47) ~[?:?]
        at org.bukkit.craftbukkit.v1_14_R1.scheduler.CraftTask.run(CraftTask.java:84) ~[patched_1.14.4.jar:git-Paper-153]
        at org.bukkit.craftbukkit.v1_14_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:54) ~[patched_1.14.4.jar:git-Paper-153]
        at com.destroystokyo.paper.ServerSchedulerReportingWrapper.run(ServerSchedulerReportingWrapper.java:22) ~[patched_1.14.4.jar:git-Paper-153]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.8.0_221]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.8.0_221]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_221]