General Exception Error from word-win32-16.00.js:19:150094)n at yi

I have a 100 or so Word Open XML (.xml, not .docx, saved as "Word XML Document")documents (components) stored on SharePoint. I use AJAX to load these by selection, as xml, 1 to many into an array, in which I also manage the selection sequence. Once the user has selected the "components" they can then insert them into Word, the insertion is done via an array traversal (there is probably a better way to do this - but for now it does work), wordBuild does the loading function writeDocSync(){ // run through nameXMLArray to find the right sequence var x = 0; var countXMLAdds = 0; //debugger; toggleWriteButton("disable"); $('.progress-button').progressInitialize("Building Word"); toggleProgressBar(true); // only run if we have data present if(nameXMLArray.length > 0){ // increment through sequentially until we have all values while (countXMLAdds <= checkedList.length){ // repeatedly traverse the array to get the next in sequence while (x < nameXMLArray.length){ if (Number(nameXMLArray[x].position) === countXMLAdds && nameXMLArray[x].useStatus === true){ progHold = countXMLAdds; wordBuild(nameXMLArray[x].xml, nameXMLArray[x].filename, countXMLAdds); } x++; } x=0; countXMLAdds ++; } document.getElementById("showCheck").className = "results"; writeSelections("<b>You just built your proposal using<br/>the following components:</b><br/>"); toggleWriteButton("enable"); } } xxxxxxxxx function wordBuild(xmlBody, nameDoc, progress){ var aryLN = checkedList.length; var progPCT = (progress/aryLN)*100; progressMeter.progressSet(progPCT); Word.run(function (context) { var currentDoc = context.document; var body = currentDoc.body; body.insertOoxml(xmlBody, Word.InsertLocation.end); body.insertBreak(Word.BreakType.page, Word.InsertLocation.end); return context.sync().then(function () { showNotification("Written " + nameDoc); }); }) .catch(function (error) { showNotification('Error: ' + nameDoc + ' :' + JSON.stringify(error)); if (error instanceof OfficeExtension.Error) { showNotification('Debug info: ' + JSON.stringify(error.debugInfo)); } }); } All the documents will load singly, and all will load in batches of say 10 - 30 or more. The problem comes when I load the entire set (I have a "check all" option). Sometimes 50 will build before I get an exception, sometimes 60, rarely more than 60, but very occasionally I get a gap where the exception doesn't occur, then it continues later. The exception (which is repeated for each file) is: Debug info: {} Error: componentABC.xml :{"name":"OfficeExtension.Error","code":"GeneralException","message":"An internal error has occurred.","traceMessages":[],"debugInfo":{},"stack":"GeneralException: An internal error has occurred.n at Anonymous function (https://customerportal.sharepoint.com/sites/components/Shared%20Documents/componentAssembler/Scripts/Office/1/word-win32-16.00.js:19:150094)n at yi (https://customerportal.sharepoint.com/sites/components/Shared%20Documents/componentAssembler/Scripts/Office/1/word-win32-16.00.js:19:163912)n at st (https://customerportal.sharepoint.com/sites/components/Shared%20Documents/componentAssembler/Scripts/Office/1/word-win32-16.00.js:19:163999)n at d (https://customerportal.sharepoint.com/sites/components/Shared%20Documents/componentAssembler/Scripts/Office/1/word-win32-16.00.js:19:163819)n at c (https://customerportal.sharepoint.com/sites/components/Shared%20Documents/componentAssembler/Scripts/Office/1/word-win32-16.00.js:19:162405)"} Any help with what might cause this would be hugely appreciated. Oh I should also say, the files where the exception is raised don't get inserted into Word. But in smaller batches - they work without issue.