I'm seeing the same thing on Ubuntu 18.04.
A quick google of the error tells me it's related to this:
Upgrades
Infra/Packaging
- Upgrade the bundled JDK to JDK 15 #62580
UPDATE:
So my automated approach of updating elasticsearch ignores any new versions of configuration files. Forcing reinstall using sudo apt install --reinstall -o Dpkg::Options::="--force-confask,confnew,confmiss" elasticsearch gave me an updated jvm.options that solves the issue. Here's the diff:
# diff jvm.options jvm.options.dpkg-old
36,38c36,38
< 8-13:-XX:+UseConcMarkSweepGC
< 8-13:-XX:CMSInitiatingOccupancyFraction=75
< 8-13:-XX:+UseCMSInitiatingOccupancyOnly
---
> -XX:+UseConcMarkSweepGC
> -XX:CMSInitiatingOccupancyFraction=75
> -XX:+UseCMSInitiatingOccupancyOnly
41,48c41,47
< # NOTE: G1 GC is only supported on JDK version 10 or later
< # to use G1GC, uncomment the next two lines and update the version on the
< # following three lines to your version of the JDK
< # 10-13:-XX:-UseConcMarkSweepGC
< # 10-13:-XX:-UseCMSInitiatingOccupancyOnly
< 14-:-XX:+UseG1GC
< 14-:-XX:G1ReservePercent=25
< 14-:-XX:InitiatingHeapOccupancyPercent=30
---
> # NOTE: G1GC is only supported on JDK version 10 or later.
> # To use G1GC uncomment the lines below.
> # 10-:-XX:-UseConcMarkSweepGC
> # 10-:-XX:-UseCMSInitiatingOccupancyOnly
> # 10-:-XX:+UseG1GC
> # 10-:-XX:G1ReservePercent=25
> # 10-:-XX:InitiatingHeapOccupancyPercent=30
I'm no Java expert, so to summarize: Make sure you use the latest jvm.options (don't forget to save a backup of your old one in case of custom modifications) and hopefully elasticsearch starts just fine.