Two days ago I was updated WP to version 4.9.9 automatically.
after the update I was able to import CSV without problem.
The problem appeared later without any type of update or plugin installation.
I have tried to load some recently downloaded csv file without modifying it and it gives the same error.
I have checked the plugins that I have installed and not any modification.
there is also a line up as with an error:
…. wallets / includes / transactions.php on line 1203
I would only have to try option 3 but I would not like to have a security problem.