Upgrade D6 to D8 : migrate run stops with an error

When upgrading with the Drupal migrate module i first got problems with 'url-aliases'. There wher more then 56,000 and the migrate module stops with an error. I then truncate te table and start again. Now I'm migrating about 25,000 nodes and got also an error. When it stops and i rerun the migrate module i see that now the nodes are migrated one by one...

Currently upgrading Nodes (adresarchief) (51 of 121 total tasks)
Continuing with Nodes (adresarchief) (processed 1 item)
Continuing with Nodes (adresarchief) (processed 1 items)
Continuing with Nodes (adresarchief) (processed 1 items)
Continuing with Nodes (adresarchief) (processed 1 item)
Continuing with Nodes (adresarchief) (processed 1 items)
Continuing with Nodes (adresarchief) (processed 1 items)
Continuing with Nodes (adresarchief) (processed 1 items)
Continuing with Nodes (adresarchief) (processed 1 items)
Continuing with Nodes (adresarchief) (processed 1 items)
Continuing with Nodes (adresarchief) (processed 1 items)
Continuing with Nodes (adresarchief) (processed 1 items)
Continuing with Nodes (adresarchief) (processed 1 items)
Continuing with Nodes (adresarchief) (processed 1 items)
Continuing with Nodes (adresarchief) (processed 1 items)
Continuing with Nodes (adresarchief) (processed 1 items)
Upgraded Upload field instance configuration (processed 0 items total)
Upgraded Upload field configuration (processed 0 items total)
Upgraded Field formatter configuration (processed 0 items total)
Upgraded View modes (processed 0 items total)

And the error message i got is

Er is een fout opgetreden.
Ga verder naar de foutmeldingspagina
Een AJAX HTTP-aanvraag is onverwacht afgebroken
Debug informatie volgt.
Pad: /drupal8/batch?id=27&op=do_nojs&op=do
Statustekst: error
Antwoordtekst:
ReadyState: 0

I have for so far as I know no acces to the command line. I run the update at my providers place. Should I run it local?

Can some one help?

Thanks,
Fred