I have a shapefile with a relatively extensive attribute table. I extended it by adding geometry data ("Vector > Geometry tools > Export/Add geometry columns") and now I cannot save the layer in a new file. When I try to save it as an ESRI shapefile, I get a message: Export to vector file failed. Error: creation of field T4_3FTC failed (OGR error: Can't create field T4_3FTC in Shape DBF file, reason unknown.)
When I try to save it as a Geopackage file, I get a message: Export to vector file failed. Error: creation of field fid failed (OGR error: Wrong field type for fid)
When I try to save it as a CSV file, the program crashes and I lose my work (tried at least three times).
Apart from that, the file works perfectly, the attribute table isn't corrupted in any way. What should I do to fix the issue?
Edit: the program finally generated a CSV file after around 5 minutes of being unresponsive. Still no luck with other formats.