Problem with Session.vim file

[J S]

vim version is 8.0, p1453

system is Ubuntu 18.04

I built up a complicates set of windows and tabs in GVIM and saved it as Session.vim

When I reload from that file (after a reboot), I get error E35: Not enough room

The offending line in the Session.vim file is:

set winminheight=1 winheight=1 winminwidth=1 winwidth=1

Experimentation shows that it is the first of these that is causing the problem (it maybe others, of course, since it crashes on the first one) and that somehow this has gotten set to 0 (such that my windows are "squashed", as described in the help file for this option). Trying to set it to 1 (the default value) generates the above-mentioned error (Not enough room).

I was able to fix (kludge around) this by commenting out all the lines that involve these options (about 7 of them in a 1349 line Session.vim file), but of course, this is not the real/right fix.
But do note that once I commented them all out, the file loaded and displayed my windows and tabs correctly.