Error(s) in re-building vignettes:
--- re-building ‘abc.Rmd’ using rmarkdown
dyld: lazy symbol binding failed: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

dyld: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

Error: processing vignette 'abc.Rmd' failed with diagnostics:
pandoc document conversion failed with error 6
--- failed re-building ‘abc.Rmd’

--- re-building ‘furthernotes.Rmd’ using rmarkdown
dyld: lazy symbol binding failed: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

dyld: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

Error: processing vignette 'furthernotes.Rmd' failed with diagnostics:
pandoc document conversion failed with error 6
--- failed re-building ‘furthernotes.Rmd’

--- re-building ‘getstarted.Rmd’ using rmarkdown
dyld: lazy symbol binding failed: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

dyld: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

Error: processing vignette 'getstarted.Rmd' failed with diagnostics:
pandoc document conversion failed with error 6
--- failed re-building ‘getstarted.Rmd’

--- re-building ‘optimization.Rmd’ using rmarkdown
dyld: lazy symbol binding failed: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

dyld: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

Error: processing vignette 'optimization.Rmd' failed with diagnostics:
pandoc document conversion failed with error 6
--- failed re-building ‘optimization.Rmd’

--- re-building ‘sensitivity.Rmd’ using rmarkdown
dyld: lazy symbol binding failed: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

dyld: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

Error: processing vignette 'sensitivity.Rmd' failed with diagnostics:
pandoc document conversion failed with error 6
--- failed re-building ‘sensitivity.Rmd’

--- re-building ‘simdesign-examples.Rmd’ using rmarkdown
dyld: lazy symbol binding failed: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

dyld: Symbol not found: ____chkstk_darwin
  Referenced from: /usr/local/bin/pandoc (which was built for Mac OS X 10.15)
  Expected in: /usr/lib/libSystem.B.dylib

Error: processing vignette 'simdesign-examples.Rmd' failed with diagnostics:
pandoc document conversion failed with error 6
--- failed re-building ‘simdesign-examples.Rmd’

SUMMARY: processing the following files failed:
  ‘abc.Rmd’ ‘furthernotes.Rmd’ ‘getstarted.Rmd’ ‘optimization.Rmd’
  ‘sensitivity.Rmd’ ‘simdesign-examples.Rmd’

Error: Vignette re-building failed.
Execution halted