Stop Anki Blocking Card Review

Anki blocks card reviews when its database locks, storage is full, or add-ons conflict with the current version. To resume your German learning deck immediately, close all Anki instances completely, clear temporary lock files in the profile folder, and disable recently installed add-ons to restore normal review functionality.

Understanding the Review Block Mechanism

When Anki prevents you from reviewing cards, it is usually protecting your data from corruption. The application uses a locking mechanism to ensure that only one process accesses the database at a time. If this lock file remains after a crash or improper shutdown, Anki assumes another instance is running and refuses to start the review queue. This is a safety feature, not a bug, but it can be frustrating when you are trying to maintain your daily streak for your German vocabulary deck. The block often manifests as an error message stating that Anki is already running, or simply freezing on the startup screen without loading any cards. In some cases, the interface appears normally, but the "Review" button is grayed out or unresponsive. Understanding this mechanism helps you diagnose whether the issue is a simple file lock or a deeper configuration problem.

Clearing Lock Files and Temp Data

The most common cause of this issue is a stale lock file left behind by a previous session. You need to manually remove these files to allow a fresh instance of the application to start. First, ensure that no Anki processes are running in the background. On Linux, you can use the ps aux | grep anki command to check for lingering processes and kill them if necessary. On Windows and macOS, use the task manager or activity monitor to quit the application forcefully. Once the application is fully closed, navigate to your Anki profile directory. This folder contains your collection media, notes, and the critical lock files. Look for files named .lock or collection.anki2.lock. Delete these files carefully. Do not delete the main collection file itself, as that contains your actual learning data. After removing the lock files, restart Anki. The application should now initialize the database without detecting a conflicting process. If clearing the lock files does not resolve the issue, you may need to clear the temporary cache. Navigate to the appdata or cache folder within your Anki profile directory. Remove the contents of the cache folder, but keep the folder structure intact. This forces Anki to rebuild its local cache upon next launch, which can resolve rendering issues that mimic a review block. For users managing multiple systems, ensuring consistent synchronization is key. If you are syncing across devices, conflicts can sometimes cause review blocks. Ensure that you have completed a successful sync on all devices before attempting to review. If you suspect a sync conflict, refer to our guide on exposing local server configurations to understand how network settings might affect data integrity, although this is less common for desktop-only users.

Disabling Conflicting Add-ons

Add-ons extend Anki's functionality but are a frequent source of stability issues. When Anki updates, older add-ons may become incompatible, causing the review engine to fail silently or throw errors. To identify the culprit, start Anki in safe mode. This disables all add-ons temporarily. Go to the Tools menu and select Safe Mode. If the review block disappears in safe mode, an add-on is definitely the cause. Restart Anki normally and go to Tools > Add-ons. Disable all add-ons one by one, restarting Anki after each disablement to test if the review function returns. Start with recently installed or updated add-ons, as these are the most likely to cause conflicts. Common problematic add-ons include those that modify the review interface, change card timing, or integrate with external tools like speech recognition for language learning. Once you identify the problematic add-on, check for updates on the official AnkiWeb repository. If an update is available, install it. If not, consider disabling the add-on permanently or finding an alternative that is compatible with your current Anki version. Maintaining a lean set of add-ons reduces the risk of future conflicts and keeps your learning workflow smooth.

Managing Storage and Media

Anki requires sufficient disk space to operate correctly. If your drive is nearly full, the application may fail to write temporary review data, resulting in a block. Check your available disk space and free up room if necessary. Additionally, large media files attached to your German cards can slow down the application. Use the Tools > Check Media feature to find unused files and remove them to optimize performance.

Rebuilding the Database Index

In rare cases, the internal index of your collection may become corrupted. Anki provides a built-in tool to repair this. Go to Tools > Check Database. This process verifies the integrity of your collection and repairs any inconsistencies. It may take several minutes depending on the size of your deck. After the check completes, restart Anki. This step is crucial for long-term health of your learning data. For advanced users who manage their own backups, regular exports are essential. Export your collection regularly to prevent data loss during unexpected crashes. If you encounter persistent issues, restoring from a recent backup can resolve deep-seated corruption that standard repair tools cannot fix.

Frequently Asked Questions

Why does Anki say it is already running when I am sure it is closed?

This occurs because a background process or a stale lock file remains active. Even if you close the window, the application may still be running in the system tray or background. You must explicitly quit the application using the right-click menu or task manager to release the lock.

Can I recover my German cards if the database is corrupted?

Yes, provided you have exported your collection previously. Anki allows you to import .apkg files to restore your decks. Always create backups before performing major updates or troubleshooting steps to ensure you can revert changes if they cause further issues.

Does clearing the cache delete my learned progress?

No, clearing the cache only removes temporary files used for displaying images and formatting text. Your learning schedule, due dates, and card content are stored in the main database file, which remains untouched during a cache clear operation.

How do I know which add-on is causing the review block?

Use the safe mode diagnostic method. Disable all add-ons, then re-enable them one by one while testing the review function after each change. The add-on that causes the block when enabled is the culprit. Focus on add-ons related to interface customization or audio playback first.

Is it safe to delete the .lock file manually?

It is safe only if you are certain that no other instance of Anki is running. Deleting the lock file while Anki is active can lead to database corruption. Always verify that the application is fully closed via the task manager before deleting any lock files.