'System is temporarily unavailable' error for View Email as Web Page

The 'View Email as Web Page' (VAWP) link stays active for as long as the URL Expiration policy allows, however it can also be inactive due to several reasons discussed in this article.

How VAWP Works?
When a subscriber clicks the VAWP link, the system reconstructs the email by looking up the original send data. The behavior differs depending on the send type:

The typical reason for an unavailable VAWP link and displaying the error message is the following: 

Common Reasons for VAWP Link Failure

1. Data Retention Expiration (Triggered Sends & Journey Builder)

For Triggered Sends and Journey Builder email sends, the personalization data stored at send time is subject  to a retention policy. Once this data is purged (default: 30 days), the VAWP link can no longer reconstruct the email.
How to check: Your account's URL Expiration setting controls this retention period. Contact your account team if you need it extended (maximum: 2 years).

2. Data Extension or List Data Modified/Deleted (Guided Sends)

For Guided Sends, the VAWP link performs a live lookup against the source Data Extension or List each time the page is rendered. If the data has been overwritten, updated, or deleted since the original send, the VAWP page will either display incorrect personalization or fail entirely.
This also affects Triggered/JB sends if they reference dynamic data lookups (e.g., Lookup() or LookupRows() AMPScript functions) that point to data outside the stored send-time snapshot.

3. Contact Deletion

If a contact/subscriber is deleted from the system, the VAWP link will fail regardless of send type, as the system can no longer resolve the subscriber identity needed to render the page.

4. URL Expiration Policy

All VAWP links are ultimately governed by the account-level URL Expiration setting. Once this threshold is passed, the link will no longer function even if the underlying data still exists.

Workaround

1. Implement Send Logging 

To use this, you'll create a new Data Extension for this purpose and use the 'SendLog' template and reference this at the time of send. 

Send Logging

Once you have implemented a send log, this will then require additional AMPScript in your emails, which logs the send and required personalization data to a central data extension. When the VAWP link is clicked, the page will pull the required data from this SendLog Data Extension, as opposed to the original SF Data Extension. See the documentation Display Send-Time Content Contextually.
 

2. Import Activity 

An alternate option would be to use an Import Activity within the Marketing Cloud interface to import the report into a Data Extension and send via a Guided Send. This way you can set the retention policy as per your requirements.