WebStorm doesn't start after latest update

do you have idea.log created in ~/Library/Logs/JetBrains/WebStorm<your version> folder? If yes, could you share it?
also, please try starting the IDE from terminal - what is printed to console?

The Library/Logs/WebStorm2019.3/idea.log file is quite long, with many errors. I don't want to post it all here. Can I mail it somewhere?

When starting Webstorm in a terminal I get the following:

Pern:Applications fromherz$ /Applications/WebStorm.app/Contents/MacOS/webstorm 
2020-05-06 14:16:22.151 webstorm[9042:303612] allVms required 1.8*,1.8+
2020-05-06 14:16:22.191 webstorm[9042:303628] Cannot load JVM bundle: Error Domain=NSCocoaErrorDomain Code=3587 "dlopen_preflight(/Applications/WebStorm.app/Contents/jbr/Contents/MacOS/libjli.dylib): no suitable image found. Did find:
/Applications/WebStorm.app/Contents/jbr/Contents/MacOS/libjli.dylib: code signature invalid for '/Applications/WebStorm.app/Contents/jbr/Contents/MacOS/libjli.dylib'

/Applications/WebStorm.app/Contents/jbr/Contents/MacOS/libjli.dylib: stat() failed with errno=1" UserInfo={NSLocalizedFailureReason=The bundle is damaged or missing necessary resources., NSLocalizedRecoverySuggestion=Try reinstalling the bundle., NSFilePath=/Applications/WebStorm.app/Contents/jbr/Contents/MacOS/libjli.dylib, NSDebugDescription=dlopen_preflight(/Applications/WebStorm.app/Contents/jbr/Contents/MacOS/libjli.dylib): no suitable image found. Did find:
/Applications/WebStorm.app/Contents/jbr/Contents/MacOS/libjli.dylib: code signature invalid for '/Applications/WebStorm.app/Contents/jbr/Contents/MacOS/libjli.dylib'

/Applications/WebStorm.app/Contents/jbr/Contents/MacOS/libjli.dylib: stat() failed with errno=1, NSBundlePath=/Applications/WebStorm.app/Contents/jbr, NSLocalizedDescription=The bundle “OpenJDK 11.0.3” couldn’t be loaded because it is damaged or missing necessary resources.}

I was able to download and install Webstorm 2020.1.1, which worked immediately.

Such issues may occur when multiple conflicts are found in the 'jbr/' directory when applying the patch (files have checksums that are different from the expected ones); we have a request to avoid applying the patch in such cases to avoid issues,  https://youtrack.jetbrains.com/issue/IDEA-117181

Just posting this in case anyone else is dumb like me.

Spent awhile searching for logs and seeing what was up whilst trying to launch WS from the toolbox. It turned out Webstorm process was already running but not visible in the dock.  Force quitting it solved the issue.