After looking up https://www.lizardtech.com/gis-tools/plug-ins I see no mention of Deja Vue on the web site,

It maybe possible to run them in 52.5.0 ESR. It will continue to get security updates until May 2018, and you can download and install it from this page: https://www.mozilla.org/en-US/firefox/organizations/all/ Note : Legacy Extensions will be deleted or removed in any version update after May 2018.

You should make a backup of your Profile before going back and just because: https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Note : Will need to uninstall current version. Difficult to get 2 to run at same time as will share same profile.

If not please update current version ; https://support.mozilla.org/en-US/kb/update-firefox-latest-version to 57.0.2

Searching Firefox Extensions I found similar named programs but seems they were abandoned 7- 8yrs ago

If this is a paid program chase them down, if not maybe will have to find a replacement that will open those files. I hope they are not stuck in there.

Can try here : https://addons.mozilla.org/en-US/firefox/extensions/

Please let us know if this solved your issue or if need further assistance.

See also:

• https://en.wikipedia.org/wiki/MrSID
• https://www.google.com/search?q=mrsid

Need latest version 57.02 for other tasks.

The file extension not opening is MrSid

The National Land Survey of Sweden and their historical maps use MrSid. Tried to use another programme on Lizardtech homepage but it didn´t work either. But it´s no big deal. Sweden has 10 million inhabitants can´t expect to much work for such a little group. So Explorer will do. Anders

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