Are you still looking for a solution to the error ‘ModSecurity failed deleting collection’? Then take a peek at this blog.

Here at Bobcares, we have seen several such ModSecurity errors as part of our Server Management Services for web hosts, and online service providers.

Today we’ll take a look at the causes for this error and see how to fix it.

What does ‘ModSecurity failed deleting collection’ error mean

ModSecurity has a system called collections that are used to create arrays and store information. Primarily we use these collections as a performance enhancement.

It supports persistent collections i.e. variables are available only over requests.

These persistent collections maintain an in-memory cache and syncs with the SDBM storage in a timely manner. Each process on the webserver has a different in-memory collection that syncs with SDBM storage.

Also, these collections have the ability to remove details from arrays. But, it is only possible when a request occurs, because ModSecurity doesn’t have any execution logic as it is trigger based.

Sometimes, when a trigger initiates to remove the entries from the array, it might have been already removed from some other process. So this error occurs.

For instance, the error appears as below,

[error] [client xxx.xxx.xxx.xxx] ModSecurity: collections_remove_stale: Failed deleting collection (name “ip”, key “xxx.xxx.xxx.xxx_9e5f93x096exxxxxxxxxxxxxxxxx26fa765”): Internal error [hostname “www.example.com”] [uri “/php5-fcgi/setting/list.php”] [unique_id “UkxkMMaIMEoAADg9zw0xxxxx”]

How we fix ‘ModSecurity failed deleting collection’ error

Now let’s see the suggestions our Support Engineers provide to tackle this error.

1. Try reducing the expiration time to a lower value of persistent collections. As a result, it will reduce the amount of register in a given collection.

2. Try making any changes in the rules so that it will reduce the size of the collection.

3. In some cases, data file storage will be high creating some problems. Here are a few things to check:

• Check your data files storage(SecDataDir) path and see if this is causing any slowness. consider cleaning up tmp directory.
• Try to set SecDataDir to its own dedicated directory.
• Also, you can try to set SecDataDir to a tmpfs or memory filesystem.

[Need any further assistance in fixing ModSecurity errors? – We are here to help you.]

Conclusion

Today, we discussed the reason for this error and also the suggestions our Support Engineers provided.