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Error Troubleshooting Guide For Craft CMS SEO: Failed To Retrieve Entry Preview

10 min read
Shape April 2022 HR 197

Dealing with "Failed to retrieve entry preview" errors in Craft CMS? This frustrating issue can completely block publishing workflows and damage site quality. In this guide, we’ll share step-by-step troubleshooting tips, quick fixes and preventative solutions from Craft experts to master resolving retrieval failures. Read on to squash this error for good and restore smooth CMS editing.

A complete troubleshooting methodology for the "Failed to retrieve entry preview" error in Craft CMS. It covers the error's meaning, 10+ causes, step-by-step debugging, 5 quick fixes, and 3 preventative solutions, allowing editors to systematically resolve preview failures for smooth publishing.

Understanding the "Failed to Retrieve Entry Preview" Error

When working in Craft CMS as a content editor or website administrator, one of the more common errors you may encounter is the "Failed to retrieve entry preview" message. This error can surface during the vital process of previewing draft content, leading to frustration and blocking workflow. In this section, we'll analyse why the error occurs, what the message means, and the impacts it can have.

When the Error Occurs

The "Failed to retrieve entry preview" error will arise at the point when a user attempts to generate a preview of an entry draft within the Craft CMS content editing interface.

Some specific actions that can trigger it include:

  • Clicking the "Preview draft" button on an existing entry revision.

  • Selecting "Preview draft" from the options next to an unsaved entry draft.

  • Attempting to preview an entry with validation issues before it can be saved as a proper draft.

Essentially any time the content editor tries to retrieve and display an early preview of an entry, there is potential for failure and this error emerging. It's most likely to occur when previewing entry drafts, as the error message indicates.

Understanding the exact reproduction steps here is useful, as it points to an issue with retrieving entry draft data from the server into the preview view.

Meaning of the Error Message

The error message itself - "Failed to retrieve entry preview" - succinctly communicates the root cause of the problem.

Breaking it down:

  • "Failed to" shows there was an unsuccessful attempt at some action.

  • "Retrieve" means obtaining or fetching data.

  • "Entry preview" specifies the exact data - a preview of an entry draft.

Combined, the message indicates the CMS failed to obtain the entry draft preview information from the server when the user triggered the preview action.

This points to a communication breakdown between the content editing interface the underlying Craft CMS install and database. The entry draft data cannot be selected and displayed as expected in preview mode.

Impact of the Error

At first glance this may seem like a minor error with limited impact. However, given the vital nature of previewing content drafts prior to publishing, it can have wider implications.

When this error occurs, the content editor has no way to preview draft entry changes as they are made. This means mistakes can be introduced and only identified after content is live after publishing.

It also prevents proper QA of entries before public visibility, leading to spelling errors, formatting issues, broken links and other problems reaching your site live.

This has multiple knock-on effects:

  • Frustration for content teams unable to preview properly.

  • Embarrassment if draft content isn't previewed but publishes with issues.

  • Loss of SEO traffic and reputation from poor content quality.

  • Negative user experience from broken pages or links.

Clearly then while a relatively minor technical error, "Failed to retrieve entry preview" can significantly impact editing workflows, content quality and ultimately site visitor satisfaction.

Diagnosing the underlying cause - often a plugin conflict, server misconfiguration or Craft CMS bug - and implementing a fix should be a high priority. Dedicated monitoring and alerts for this error are also advised.

While irritating, catching and resolving this issue helps ensure smooth, clean content drafting and reduces the risk of mistakes impacting end users. With a debug and solution process in place, its negative effects can be minimised.

Common Causes of "Failed to Retrieve Entry Preview" Error

When the frustrating "Failed to retrieve entry preview" error pops up in Craft CMS, it's usually triggered by an underlying issue with user accounts, draft tokens or other factors. Diagnosing the specific cause is key to resolving it. In this section we'll explore some of the most frequent triggers for this error.

Incorrect User Permissions

One of the most common reasons the entry preview retrieval error occurs is incorrect user account permissions.

Within Craft CMS, specific user roles and accounts can be granted or denied access to manage various content entry types. For example, an "Editor" role might have permissions to edit and publish blog posts, but not landing pages.

If a user account lacks the right permissions to manage and preview a particular entry type, the "Failed to retrieve entry preview" error can emerge when they try to view a draft.

The system is essentially saying this user cannot access or preview this draft content based on their account role.

Double checking the user has the right content entry permissions for the section they are

previewing is a good first troubleshooting step. If permissions are incorrectly configured, no amount of draft token refreshing will help.

Updating the user role, group or account permissions to allow proper entry management access is key to resolving the preview failure.

Invalid Entry Draft Token

Another very common trigger is an expired or invalid entry draft token.

In Craft CMS, when an editor begins modifying an existing draft or creating a new entry, a unique temporary preview token is generated.

This token allows retrieving the draft content from the server to display in the preview pane.

However, these tokens eventually expire - often after a few hours. If the editor returns to an entry draft after the token has expired, the "retrieve entry preview" process will fail, producing the error.

Similarly, if the draft token becomes invalid or corrupted for any reason, the same will occur.

Refreshing the entry draft or forcing regeneration of the preview token will typically resolve token-related occurrences of this error.

Other Common Causes

Aside from user permissions and preview tokens, there are a few other frequent causes of failed entry preview retrieval:

  • Server Misconfigurations: Craft CMS requires specific server settings for smooth operation. Any misconfigurations like incorrect PHP versions, server resource limits, or caching settings can lead to this error when performing complex preview operations.

  • Craft CMS Bugs: Like any CMS, Craft can suffer bugs and glitches after updates or due to plugin conflicts. These can sometimes interrupt the entry preview process and cause failures. Keeping Craft CMS and plugins updated helps mitigate this.

  • Template Issues: If the templates powering entry previews rely on invalid variables, criteria or markup, it can trigger an error on fetch. The same is true if entries use fields missing from the preview template.

  • Plugin Conflicts: 3rd party plugins that modify entry behaviours, editing interfaces or preview capabilities can sometimes interfere with core CMS functions leading to this error. Disabling non-essential plugins can help isolate conflicts.

While permissions and tokens make up the bulk of cases, these other sources of "Failed to retrieve entry preview" errors are worth examining during troubleshooting. A misbehaving plugin or Craft bug could easily be the culprit.

Pinpointing what is disrupting the preview process is essential to crafting a solution. In some cases, it may require direct support from the Craft CMS developer team to identify and resolve the deepest underlying trigger.

Some debugging techniques like previewing entries logged in as the admin user, disabling plugins, and clearing caches can help narrow down causes. Understanding the range of possibilities provides a wider perspective and starting point.

With knowledge of the varied sources of "Failed to retrieve entry preview" errors, diagnosing the issue becomes much more achievable. A bit of testing and isolation of potential triggers will ultimately uncover what needs addressed. Eliminating the error then restores smooth entry drafting and publishing.

Troubleshooting Steps for "Failed to Retrieve Entry Preview" Error

When the dreaded "Failed to retrieve entry preview" error strikes in Craft CMS, having a clear methodology to isolate the cause is invaluable. By methodically checking common issues like permissions and preview tokens, the root of the problem can be uncovered. This section outlines a step-by-step troubleshooting approach.

Checking User Permissions

Since incorrect user permissions are a frequent source of entry preview failures, validating role access should be the first troubleshooting step.

To check permissions:

  • Go to Settings -> Users in the Craft CMS admin and open the target user account.

  • Switch to the "Permissions" tab and find the relevant entry type section (e.g. "Blog Posts").

  • Check that user permissions are enabled for "Edit entries in this section" and "Publish entries in this section".

  • If permissions are disabled or missing, enable them or switch the user to a role with proper entry rights.

With entry permissions validated, try previewing the draft again. If the error persists, move on to examining the preview token.

Validating Preview Token

If user role permissions are fine, troubleshoot the preview token:

  • While editing the draft entry, look in the browser URL bar for the ?token= parameter value.

  • Open a new tab and go to Settings -> Entries in the Craft admin.

  • Find the draft entry by ID and click to open it.

  • Check if the current draft token value matches what's in the edit URL.

  • If they do not match, refresh the token on the edit page and update the URL token.

With a matched valid preview token, retry the draft preview. If the error remains, also try disabling any plugins related to entries or editing.

Publishing Entry Draft

If all else fails and the entry preview simply will not work, publishing the entry draft directly can act as a workaround.

  • On the broken draft entry editor page, use the "Share" button to grab the entry URL.

  • Go to Settings -> Entries and open the draft.

  • Click "Publish" and select a past or current publish date.

  • Return to the entry URL from the draft - it should now be live.

While not optimal for QA, publishing the draft directly will at least allow previewing it live on the front-end.

This can help in a pinch while the deeper issue is investigated offline without blocking writing workflows. If previews remain broken, publishing may be needed as a temporary solution.

Further Troubleshooting

If the standard checks don't uncover the issue, some further techniques to try include:

  • Previewing entries while logged in as Admin - permissions are not a factor.

  • Disabling plugins one-by-one related to entries, editing or craft monitoring.

  • Switching the entry type or creating a plain test entry.

  • Clearing all caches and trying a new incognito/private window.

  • Checking for server errors in logs during the preview failure.

  • Ensuring the server meets Craft CMS requirements.

  • Opening a support ticket with detailed reproduction steps.

With persistence, the cause of "Failed to retrieve entry preview" errors in Craft can always be unearthed through systematic elimination of potential factors. By following these troubleshooting steps, content editors can rule out common causes and restore smooth entry drafting. While frustrating, determining the underlying trigger is extremely worthwhile for a long-term solution.

Quick Fixes for "Failed to Retrieve Entry Preview" Error

When encountering the "Failed to retrieve entry preview" error, trying a few quick fixes can sometimes resolve the issue immediately without deep troubleshooting. Clearing caches, refreshing tokens and switching browsers are fast options to attempt.

Clearing Caches

One easy first step is to clear all Craft CMS caches related to entries and data APIs. Over time, cached elements can become outdated, corrupt or incompatible with entry drafts causing preview failures.

To clear Craft CMS caches:

  • In the Craft admin, go to Settings -> Utilities

  • Under the Tool heading, click on Clear Caches tool.

  • Check the box for “Clear data caches” and click Submit.

  • This will purge all entry, element, and API data caches.

With caches flushed, any outdated artifacts or references that may be clashing with entry draft previews are removed. The error may immediately disappear.

If it persists, clearing caches still eliminates one potential factor and is a good general habit for Craft troubleshooting. Quick to try with no downside besides needing to rebuild caches over time.

Refreshing Preview Token

Another fast fix is refreshing the entry draft's preview token directly. As outlined earlier, an expired or invalid token can lead to failed preview retrieval.

To refresh the token:

  • From the entry draft edit screen, click on the "Refresh" button next to the token in the URL bar.

  • This will instantly regenerate the token, replacing the prior stale value.

Alternatively, saving a revision or closing and reopening the draft may also refresh the token in some cases.

With a fresh valid token powering preview logic, the error may disappear. If not, trying a different browser is another worthwhile quick fix.

Testing Different Browser

Browser conflicts are a common source of intermittent issues with complex web apps like Craft CMS. Trying the entry preview in an alternate browser can rule this out.

To test browser factors:

  • Copy the entry draft edit URL so you have it handy.

  • Open the URL in another browser like Chrome if you normally use Firefox.

  • Attempt the preview process that triggers the error.

If successful, something like cached data, cookies or extensions in the original browser may be interfering.

Switching browsers isolates the frontend logic and eliminates any browser-specific quirks. A simple change that takes seconds and may instantly resolve the pesky error.

Further Quick Fixes

Some other quick fixes worth trying include:

  • Logging out and back in to your Craft account

  • Disabling plugins temporarily related to entries or editing

  • Trying the preview on a different site environment like staging

  • Creating a brand new simple test entry draft

While deeper troubleshooting may be needed, taking a few minutes to attempt these quick fixes often yields an instant solution. Clearing caches, tokens and browsers covers the most common fast fixes for "Failed to retrieve entry preview".

Long-Term Solutions for "Failed to Retrieve Entry Preview"

While quick fixes may resolve "Failed to retrieve entry preview" errors temporarily, more comprehensive long-term solutions are recommended for ongoing prevention. Keeping Craft CMS updated, monitoring system changes, and testing previews proactively can help avoid future issues.

Updating Craft CMS

One of the key long-term strategies to avoid entry preview failures is keeping your Craft CMS core and plugins up-to-date.

Craft CMS frequently releases updates containing bug fixes, performance improvements, and security patches. Updating provides:

  • Bug fixes that resolve underlying issues disrupting preview retrieval.

  • Optimisations to entry draft handling that prevents failures.

  • New features that strengthen overall system stability.

Similarly, plugin updates also incorporate fixes, enhancements, and compatibility changes that may address causes of the error.

Staying on older unsupported Craft CMS or plugin versions increases risk of preview failures as issues remain unpatched.

Regularly checking and applying available updates is the #1 long-term recommendation.

Monitoring System Changes

Close monitoring of server configurations, plugin changes, and template updates is also advised.

As covered earlier, misconfigurations and updates that modify preview logic can introduce entry retrieval errors. Changes to:

  • Web server settings like PHP versions.

  • Caching configurations and clearing routines.

  • Editing behaviour plugins or entry-related plugins.

  • Twig templates handling entry outputs.

By actively reviewing system logs and keeping track of changes via version control, potential conflicts with retrieval can be flagged before causing trouble.

Proactive change management and monitoring helps minimise surprise disruptions that obstruct previewing.

Testing Preview Before Changes

Finally, diligently testing entry preview functionality before deploying any CMS changes is key:

  • Always validate expected entry preview behaviour in a staging environment after upgrades.

  • Be sure to check preview working for multiple entry types and draft states.

  • Fix any issues before moving updated packages, plugins or templates into production.

Rigorously confirming proper operation of the preview process before launch reduces the risk of production environment retrieval failures.

A bit of upfront testing and validation goes a long way towards reliable long-term preview capabilities.

With these preventative solutions in place, "Failed to retrieve entry preview" errors can be avoided altogether rather than needing reactive troubleshooting. The key is being proactive and keeping a close eye on the CMS.

Shape April 2022 HR 202
Andy Golpys
- Author

Andy has scaled multiple businesses and is a big believer in Craft CMS as a tool that benefits both Designer, Developer and Client. 

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