Intermittent error writing notebook file to dropbox folder

[yha]

In recent versions of Pluto, I often see notebooks get stuck, with the terminal showing something like the following:

SystemError: opening file "C:\\Users\\sternlab\\Dropbox\\julia-workspace\\ElegansTimeSeries\\notebooks\\midpoints.pluto.jl": Invalid argument
Stacktrace:
  [1] systemerror(p::String, errno::Int32; extrainfo::Nothing)
    @ Base .\error.jl:174
  [2] #systemerror#68
    @ .\error.jl:173 [inlined]
  [3] systemerror
    @ .\error.jl:173 [inlined]
  [4] open(fname::String; lock::Bool, read::Nothing, write::Nothing, create::Nothing, truncate::Bool, append::Nothing)
    @ Base .\iostream.jl:293
  [5] open(fname::String, mode::String; lock::Bool)
    @ Base .\iostream.jl:355
  [6] open(fname::String, mode::String)
    @ Base .\iostream.jl:355
  [7] open(::Base.var"#360#361"{String, Tuple{}}, ::String, ::Vararg{String}; kwargs::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ Base .\io.jl:328
  [8] open
    @ .\io.jl:328 [inlined]
  [9] write
    @ .\io.jl:422 [inlined]
 [10] write_buffered
    @ C:\Users\sternlab\.julia\packages\Pluto\QSbSE\src\notebook\saving and loading.jl:127 [inlined]
 [11] save_notebook
    @ C:\Users\sternlab\.julia\packages\Pluto\QSbSE\src\notebook\saving and loading.jl:133 [inlined]
 [12] save_notebook(session::Pluto.ServerSession, notebook::Pluto.Notebook)
    @ Pluto C:\Users\sternlab\.julia\packages\Pluto\QSbSE\src\webserver\Session.jl:57
 [13] run_reactive_core!(session::Pluto.ServerSession, notebook::Pluto.Notebook, old_topology::Pluto.NotebookTopology, new_topology::Pluto.NotebookTopology, roots::Vector{Pluto.Cell}; deletion_hook::Function, user_requested_run::Bool, already_run::Vector{Pluto.Cell}, bond_value_pairs::Base.Iterators.Zip{Tuple{Vector{Symbol}, Vector{Any}}})
    @ Pluto C:\Users\sternlab\.julia\packages\Pluto\QSbSE\src\evaluation\Run.jl:140
 [14] run_reactive_core!
    @ C:\Users\sternlab\.julia\packages\Pluto\QSbSE\src\evaluation\Run.jl:70 [inlined]
 [15] (::Pluto.var"#258#262"{Bool, Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, Pluto.ServerSession, Pluto.Notebook})()
    @ Pluto C:\Users\sternlab\.julia\packages\Pluto\QSbSE\src\evaluation\Run.jl:595

Stopping and restarting the specific notebook, it resumes fine, losing some recent changes. I don't have a reproducing example, as I haven't noticed any regularity in when this occurs. But I've seen it in multiple notebooks. Based on the machines I've seen and haven't seen this on, it might be Windows specific or Dropbox related. I think the problem was introduced somewhere between 0.19.0 and 0.19.6. I have been using Pluto 0.19.0 to avoid the issue, successfully so far.