Libre Office needs JRE to run

I have installed JRE but get a message that Calc. needs JRE to run. I click okay on the message and it runs anyway.
This is a new thing for me, although I have seen other complaints about this going back a few years.
Is there a fix?

Pls, what’s your OS and LibreOffice verion?

Calc doesn’t need JRE; but one built-in extension (non-linear solver) does. So, the message might be because you are using that function; or you have some third-party extension that depends on Java. At any rate, Calc should work itself nevertheless; only some functions might be unavailable.

The other question is why it doesn’t find JRE if you have it installed; @mariosv asked for crucial information that could help to start investigating that.

…and one more question: which version JRE is installed?

My OS in Windows 8.1 Libre office Version: 5.3.7.2 (x64)
Build ID: 6b8ed514a9f8b44d37a1b96673cbbdd077e24059
CPU Threads: 4; OS Version: Windows 6.29; UI Render: GL; Layout Engine: new;
Locale: en-CA (en_CA); Calc: group
Java 8 update 151 is installed

The fix is simple, and is iterated multiple times over multiple Q&A: You need to install correct version of Java in terms of bitness - it must match the bitness of LibreOffice. If you have LibreOffice x64, then you need Java x64. If you have LibreOffice 32-bit (that has no “x64” in its version information), then you need 32-bit Java.

Java site offers 32-bit Java by default. It allows to select which Java you can download from its Java Downloads for All Operating Systems - available if you click to See all Java downloads link instead of “Agree and start free download” big red button.

It is possible to just install both 32-bit Java and 64-bit java side-by-side, and they won’t conflict with each other.

Wow, that is simple. Thanks very much.