FastCGI / PHP error whenever I try to import from Pocket

[willthong]

Environment

• Version: 2.6.4
• Installation: docker-compose (see below)
• PHP version: N/A
• OS: Debian
• Database: SQLite
• Parameters: docker-compose (see below)

Import from Pocket. I get this error:

*53 FastCGI sent in stderr: "PHP message: PHP Warning:  file_put_contents(/var/www/wallabag/data/site-credentials-secret-key.txt): Failed to open stream: Permission denied in /var/www/wallabag/src/Wallabag/CoreBundle/Helper/CryptoProxy.php on line 26PHP message: PHP Warning:  chmod(): No such file or directory in /var/www/wallabag/src/Wallabag/CoreBundle/Helper/CryptoProxy.php on line 27PHP message: PHP Warning:  file_get_contents(/var/www/wallabag/data/site-credentials-secret-key.txt): Failed to open stream: No such file or directory in /var/www/wallabag/src/Wallabag/CoreBundle/Helper/CryptoProxy.php on line 30" while reading response header from upstream, client: <client IP>, server: _, request: "GET /quickstart HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "<my host url>", referrer: "<my host url>/quickstart"

This is my docker-compose.yml:

version: '3'
services:
  wallabag:
    image: wallabag/wallabag
    environment:
      - SYMFONY__ENV__DATABASE_DRIVER=pdo_sqlite
      - SYMFONY__ENV__DATABASE_TABLE_PREFIX="wallabag_"
      - SYMFONY__ENV__MAILER_DSN=smtp://127.0.0.1
      - SYMFONY__ENV__FROM_EMAIL=wallabag@example.com
      - SYMFONY__ENV__DOMAIN_NAME=<my domain>
      - SYMFONY__ENV__SERVER_NAME="Will's Wallabag"
    ports:
      - 8395:80
    volumes:
      - /AppData2/Wallabag/images:/var/www/wallabag/web/assets/images
      - /AppData2/Wallabag/data:/var/www/wallabag/data
    healthcheck:
      test: ["CMD", "wget" ,"--no-verbose", "--tries=1", "--spider", "http://localhost"]
      interval: 1m
      timeout: 3s
    depends_on:
      - redis
  redis:
    image: redis:alpine
    healthcheck:
      test: ["CMD", "redis-cli", "ping"]
      interval: 20s
      timeout: 3s

Any help appreciated - thank you!

What steps will reproduce the bug?