Error on startup
It actually working :P
It does not.
You can also add Screenshots for a better understanding.
PhpStorm 2019.2.1
Build #PS-192.6262.66, built on August 22, 2019
Licensed to Fillip H.
Subscription is active until January 17, 2020
Runtime version: 11.0.3+12-b304.39 x86_64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
macOS 10.14.6
GC: ParNew, ConcurrentMarkSweep
Memory: 1981M
Cores: 8
Registry: run.processes.with.pty=TRUE, ide.mac.allowDarkWindowDecorations=true, ide.tree.ui.experimental=false, ide.balloon.shadow.size=0
Non-Bundled Plugins: String Manipulation, name.kropp.intellij.makefile, org.intellij.RegexpTester, com.dmarcotte.handlebars, de.espend.idea.php.annotation, org.psliwa.idea.composer, ru.adelf.idea.dotenv, zielu.gittoolbox
Plugin 'com.chrisrm.idea.MaterialThemeUI' failed to initialize and will be disabled. Please restart PhpStorm.
java.lang.NoClassDefFoundError: com/intellij/ui/tabs/newImpl/SingleHeightTabs
at com.chrisrm.idea.UIReplacer.patchTabs(UIReplacer.java:247)
at com.chrisrm.idea.UIReplacer.patchUI(UIReplacer.java:61)
at com.chrisrm.idea.MTThemeManager.activate(MTThemeManager.java:446)
at com.chrisrm.idea.MTThemeManager.activateWithColorScheme(MTThemeManager.java:395)
at com.chrisrm.idea.schemes.MTThemesComponent.activateTheme(MTThemesComponent.java:84)
at com.chrisrm.idea.schemes.MTThemesComponent.initComponent(MTThemesComponent.java:60)
at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentConfigComponentAdapter.getComponentInstance(ComponentManagerImpl.java:503)
at com.intellij.openapi.components.impl.ComponentManagerImpl.createComponents(ComponentManagerImpl.java:126)
at com.intellij.openapi.application.impl.ApplicationImpl.lambda$load$7(ApplicationImpl.java:414)
at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcess$2(CoreProgressManager.java:169)
at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:591)
at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:537)
at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:59)
at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:156)
at com.intellij.openapi.application.impl.ApplicationImpl.load(ApplicationImpl.java:414)
at com.intellij.idea.IdeaApplication.lambda$executeInitAppInEdt$5(IdeaApplication.java:150)
at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:313)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:776)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:727)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:746)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:377)
at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
Caused by: java.lang.ClassNotFoundException: com.intellij.ui.tabs.newImpl.SingleHeightTabs PluginClassLoader[com.chrisrm.idea.MaterialThemeUI, 4.5] com.intellij.ide.plugins.cl.PluginClassLoader@6b527ba5
at com.intellij.ide.plugins.cl.PluginClassLoader.loadClass(PluginClassLoader.java:75)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
... 30 more
Seconded, just hit me all of a sudden today.
Same issue
Running Arch Linux PHPStorm 2019.2

Can any of you check with another ide ? I think PS issued an update today.
Never mind, this is a version issue. Can you upgrade to the latest EAP? If not please redownload v4.4.6
Same with WebStorm. Uninstalled and re-installed WebStorm, then re-installed Material Theme and still same problem.
Same with AppCode 2019.2.1. It worked before latest theme update.
AppCode 2019.2.1
Build #OC-192.6262.61, built on August 21, 2019
Runtime version: 11.0.3+12-b304.39 x86_64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
macOS 10.15
GC: ParNew, ConcurrentMarkSweep
Memory: 2487M
Cores: 8
Registry: ide.mac.allowDarkWindowDecorations=true, ide.mac.touchbar.use=FALSE, ide.mac.file.chooser.native=false, max.suggested.heap.size=8192, ide.tree.ui.experimental=false, ide.balloon.shadow.size=0
Non-Bundled Plugins: AwesomeKotlin, com.intellij.kotlinNative.platformDeps, com.jetbrains.edu, com.intellij.plugins.watcher, org.jetbrains.kotlin.native.appcode
Since I don't want to try EAP version, I downgraded to 4.4.6 to fix.
https://plugins.jetbrains.com/plugin/8006-material-theme-ui/versions
Same with Golang 2019.2.1
Same with Pycharm 2019.2.1
hi, it also happened to my Webstorm on Mac. Webstorm 2019.2.1, Mac version
me too
Same issue with Pycharm 2019.2.1 on macOS (Mojave)
Same error on Ubuntu 18.04.3 with PhpStorm 2019.2.1
AppCode 2019.2.1/MacOS Mojave

fixed. Sorry for the troubles.
Which version are you on?
--
Elior
On 10 Sep 2019, 21:12 +0300, JMNKLS notifications@github.com, wrote:
Still there.
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You are receiving this because you modified the open/close state.
Reply to this email directly, view it on GitHub, or mute the thread.
It works, I'm good. I just had to uninstall and re-install it to get the new update. Thank you.
Most helpful comment
Since I don't want to try EAP version, I downgraded to 4.4.6 to fix.
https://plugins.jetbrains.com/plugin/8006-material-theme-ui/versions