Hi, and welcome!
Please see the FAQ: What's a reproducible example (`reprex`) and how do I do one? Using a reprex, complete with representative data will attract quicker and more answers. This is not a question that requires one, though.
In the macOS environment, this may be due to how R was installed. With R 3.6.3, there is now a notarized pkg file as well as what may well be the last of the unsandboxed versions. I'm using the notarized version and just removed and re-installed oce without issue.
This seems consistent with the error messages that the linker failed and if you are also under Catalina would seem to be strong evidence.
Here's my sessionInfo()
R version 3.6.3 (2020-02-29)
Platform: x86_64-apple-darwin15.6.0 (64-bit)
Running under: macOS Catalina 10.15.3
Matrix products: default
BLAS: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRblas.0.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRlapack.dylib
locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
attached base packages:
[1] stats graphics grDevices utils datasets methods base
loaded via a namespace (and not attached):
[1] compiler_3.6.3
If your's is consistent, my suggestion is to re-install R directly from the CRAN site, taking special care to select the notarized` version.