Image upload fails with "Cannot read properties of null" after upgrading to v2.0.0

[YongJie-Xie]

Describe the bug

After upgrading from a previous version to Answer v2.0.0, attempting to upload an image triggers a runtime exception, and the upload fails. The browser console reports the error: Cannot read properties of null.

To Reproduce

Steps to reproduce the behavior:

1. Upgrade the Answer instance to version 2.0.0.
2. Log in as a user.
3. Go to create a new Question or Answer.
4. Click the Image Upload icon in the editor toolbar.
5. Select an image file to upload.
6. See the error in the console and observe that the image does not appear.

Expected behavior

The image should upload successfully and display in the editor.

Screenshots

Platform

• Device: Desktop
• OS: Windows
• Browser: Chrome latest
• Version: v2.0.0

---

Additional Context / Workaround

Workaround:
To temporarily fix this issue without redeploying:

1. Go to Admin > Advanced > Files.
2. Default configuration:

  "max_image_size": 4,
  "max_attachment_size": 8,
  "max_image_megapixel": 40,
  "authorized_image_extensions": [
    "jpg",
    "jpeg",
    "png",
    "gif",
    "webp"
  ],
  "authorized_attachment_extensions": []

4. Click Save.
   Root Cause Analysis:
   The issue occurs because the API endpoint /answer/api/v1/siteinfo returns null for extension lists instead of an empty array [] after a fresh upgrade.

API Response (Error State):

{
  "site_advanced": {
    "max_image_size": 0,
    "max_attachment_size": 0,
    "max_image_megapixel": 0,
    "authorized_image_extensions": null,
    "authorized_attachment_extensions": null
  }
}

API Response (After Workaround):

{
  "site_advanced": {
    "max_image_size": 0,
    "max_attachment_size": 0,
    "max_image_megapixel": 0,
    "authorized_image_extensions": [],
    "authorized_attachment_extensions": []
  }
}

Code Analysis:
The error is triggered in src/components/Editor/hooks/useImageUpload.ts. The code attempts to check authorized_attachment_extensions.length > 0. Since the value is null, accessing the .length property throws the exception.

[Dinesht04]

Since the problem came after the upgrade, I looked at the migrations and maybe this inside migration v30 is the culprit? Since the schema of the authorized_image_extensions and authorized_attachment_extensions is string [ ] . Initializing these fields without a value would give nil.

answer/internal/migrations/v30.go

Lines 69 to 80 in fca80ab

	siteWrite := &schema.SiteWriteResp{}
	if err := json.Unmarshal([]byte(siteInfo.Content), siteWrite); err != nil {
	return err
	}
	// site advanced settings
	siteAdvanced := &schema.SiteAdvancedResp{
	MaxImageSize: siteWrite.MaxImageSize,
	MaxAttachmentSize: siteWrite.MaxAttachmentSize,
	MaxImageMegapixel: siteWrite.MaxImageMegapixel,
	AuthorizedImageExtensions: siteWrite.AuthorizedImageExtensions,
	AuthorizedAttachmentExtensions: siteWrite.AuthorizedAttachmentExtensions,
	}

But the values were initialized here in Migration v24 so no values in existing site_info data wouldn't make sense.

answer/internal/migrations/v24.go

Line 59 in fca80ab

content.AuthorizedImageExtensions = []string{"jpg", "jpeg", "png", "gif", "webp"}

[YongJie-Xie]

I'm not entirely sure what went wrong internally. After running the following commands:

1. docker compose pull
2. docker compose up -d

I noticed that part of my configuration appears to have been lost, including the site URL, admin email, and other related settings.