i need all block headers hash (about 500k records), i tried to get from electrum wallet files, but when i convert the file to Ascii, it doesn't have full list. please help.
It seems that since v3.1.0, Electrum does not download any more the complete blockchain_headers, but only the pieces it needs to track transactions. And installing a previous version doesn't seem to work either.
So the more direct approach is probably to download the hashes from a web like https://blockchair.com/bitcoin/blocks.
It is limited to 1 million cells for free, but as you only need "Hash" column, just:
deselect all checkboxes but "Hash", and click on "Export" selecting then "csv". Open this file with your spreadsheet app.
If you need another column, repeat the step but just with it, and Export again to a (2) file.
Open the file from (2), copy the column, and paste it next to the first column in file from (1).
as the results are both ordered by time, rows coincide and you already have the desired data!
PS: As for Electrum, it is need to install a previous version below v3. With a version 2.6.4 it seems to work and produce a complete blockchain_headers file. There's a Python script to convert it to a