can't open my .fla file and it keeps saying "an error occurred trying to open blah blah blah.fla"

click file file>save as.

once you understand you can use a jsfl file to automate the process.  i made and use:

var doc = fl.getDocumentDOM();
var uri = fl.getDocumentDOM().pathURI

if(!uri){
alert('SAVE YOUR FILE. \n\nAn initial file save is needed to establish your save directory and file name that will be used to append version numbers.');
} else {
var a = uri.split('_v');
if(a[a.length-1] && a[a.length-1].length==7 && a[a.length-1].substr(-4)=='.fla'){
// subsequent save
var version = findNextVersionNumberF(a[a.length-1]);
var prefix = a[0];
for(var i=1;i<a.length-1;i++){
prefix = prefix+'_v'+a[i];
}
var bool = fl.saveDocument(doc,prefix+'_v'+version+'.fla');
} else {
// first save
a = uri.split('.');
a[a.length-2] = a[a.length-2]+'_v000';
bool = fl.saveDocument(doc,a.join('.'));
}
if(!bool){
alert('SAVE ERROR.\n\nSave manually (eg, file>save as...)');
}
}

function findNextVersionNumberF(s){
var version = Number(s.split('.')[0]);
return formatF(version+1);
}
function formatF(n){
var s = String(n);
while(s.length<3){
s = '0'+s;
}
return s;
}

with win 10, this file goes in

C:\Users\<username>\AppData\Local\Adobe\Animate <year>\en_US\Configuration\Commands\