It says I need JRE, but it is installed.
Running LO 5.4 and JRE Version 8 update 161
Hello,
In the future please provide some minimal info in your question such as OS, LO version & in this case the bitwise of LO & JRE (32 or 64).
There is probably a few answers to correct your problem. Either your LO settings are incorrect or you have the wrong JRE/JDK installed. The answer to each is on this post - on firefox and have loaded java 32.
Another possibility is that the .odb is a connection to an Access DB (again a stab in the dark because of lack of info). If that is the case, you have probably changed from 32 to 64 bit LO & the built in connector for Access only works under 32-bit LO. To possibly connect to Access in 64-bit LO use a JDBC connector. See mdb files not loading to base for one possible solution.
If this answers your question please tick the 
(upper left area of answer). It helps others to know there was an accepted answer.
Based upon duplicate question, what type database in .odb are you connecting to - embedded, Access other external? Is the message the same? What is on Tools->Options->Libreoffice->Advanced dialog (settings mentioned in linked answer above)? Is LO 32 or 64 bit? What OS are you using? Second request for some of this info. Can’t help if not provided.
Installed JDK and I can now access the base .ODB.
Must be on Mac! Of course you never provided details as asked for. If it was a Mac you should of had this solved with the answer originally given. It was on the first link posted days ago.