I assume you are using the "Open…" command in Textastic to open the file from ownCloud. Does the same happen when you try to open and save such a file with another editor that supports the document picker like Byword?

I do not have an ownCloud server myself.

If you purchase the latest version of Textastic for iPad in iTunes on a Mac or PC or on another iOS device that runs iOS 8, you can download the last compatible version from the Purchased section in the App Store on your iOS 7 device. Just make sure you are using the same iTunes account.

This is explained in this Apple support article: http://support.apple.com/en-us/HT201377

Ah, ok, I just saw that you did successfully reference the Firebug server directly. So yes, that's the workaround in this case.

You cannot reference it locally when you use the "Open…" command, since the file is located in the Working Copy sandbox while the firebug-lite.js is located in Textastic's sandbox. You can try to use the "stable live link" version instead which references https://getfirebug.com/firebug-lite.js

Also, Textastic has only access to this single file in Working Copy and not other files in the same folder in Working Copy.

I guess combining -n and -W would work:

-n, --new Open a new instance of the application even if one is already running.
-W, --wait-apps Blocks until the used applications are closed (even if they were already running).

You could try to quit Textastic and delete the container directory:

• quit Textastic
• delete the following folder: ~/Library/Containers/com.textasticapp.textastic-mac
• restart Textastic

This should delete all preferences and saved application state.