ardour cannot find IR plugin

I have had Arch installed for about 5 years. Recently I noticed that in projects with the IR-lv2, Ardour can’t locate the plugin. I have installed Manjaro more recently with pretty much the same configuration. It will load there. Same version of IR and Ardour. Is there a blacklist for lv2? I can only find a vst blacklist.

It depends on the version of ir.lv2. When it was imported in github the id was changed, on Jan 1 2016. There was not a version bump, so it’s difficult to know which url to use. IMHO you should update to the latest version, which uses the new id URI.

I guess it’s a bit of a mess. If I change the url to, then it works in Arch but not in other distros. The factorial url still works in Mint and Manjaro,

Ok thanks. I finally got it to work by changing the URL in the session file.

Hi everyone!
@Tartina: The URL is “”, the latest code can be downloaded from “

A *.deb for (X)Ubuntu 16.04/64bit/Jacd2 compiled from the latest github-version can be downloaded from my website “

Greetings, Michael

If you have the new version of zita-convolver you need to update to 1.3.4 of Released in June, but you likely will have to compile it yourself depending on which distribution you are using.

Oh thank you. I didn’t realise that ir was still being updated.

The IR plugin some time ago changed its unique id from to
That URL is what identifies LV2 plugins for the host, so you should (after making a backup) replace the old URL with the new one in the ardour session file, the one with .ardour extension.

Seems like the problem is that zita-convolver was upgraded to ver 4. The ir plugin still works in Manjaro and Mint with ver 3.1 of zita-convolver. If I downgrade to 3.1 in Arch, Ardour crashes before it finishes starting.

I notice another now. Carla rack. They are listed in lv2ls. The log says
ERROR]: LV2: Failed to instantiate plugin
[ERROR]: Found a reference to a plugin (“”) that is unknown.
Perhaps it was removed or moved since it was last used.
They work in Ardour in Manjaro which as far as I know are using the same packages.
The plugins are installed in /usr/lib/lv2

There is no explicit LV2 blacklist, but Ardour since version 4.2 (when compiled with LV2 SDK > 1.2.0) refuses plugins that require a the buffersize to always be a power of two. Those plugins caused crashes in the past. IR.lv2 used to be one of those. The log will have a warning “LV2: buffer-size requirements cannot be satisfied”.

Perhaps there’s a different issue though. Can you run Ardour from the commandline? are there any additional messages there>

Check if lv2ls can find it. Ardour uses the same standard LV2 library as lv2ls to discover LV2 plugins … A common problem is using a version of Ardour built with an incomplete or incorrect search path built into this library, which happens with some distributions.

Ardour likely blacklists the plugin since it cannot cope with variable block-size. Check Window > Log

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