package libfftw3-doc (not installed) failed to install/upgrade: trying to overwrite '/usr/share/info/fftw3.info.gz', which is also in package imgcnv 1.66

[KEVIN KENNY]

apparent conflict with package 'imgcnv' - no idea who's right.

$ sudo apt install libfftw3-3 libfftw3-dev libfftw3-doc
Reading package lists... Done
Building dependency tree
Reading state information... Done
libfftw3-3 is already the newest version (3.3.5-3).
libfftw3-3 set to manually installed.
The following packages were automatically installed and are no longer required:
  linux-headers-4.10.0-26 linux-headers-4.10.0-26-generic
  linux-image-4.10.0-26-generic linux-image-extra-4.10.0-26-generic
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
  libfftw3-bin libfftw3-quad3
The following NEW packages will be installed:
  libfftw3-bin libfftw3-dev libfftw3-doc libfftw3-quad3
0 upgraded, 4 newly installed, 0 to remove and 14 not upgraded.
Need to get 2,877 kB of archives.
After this operation, 19.3 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://us.archive.ubuntu.com/ubuntu zesty/main amd64 libfftw3-quad3 amd64 3.3.5-3 [549 kB]
Get:2 http://us.archive.ubuntu.com/ubuntu zesty/main amd64 libfftw3-bin amd64 3.3.5-3 [31.8 kB]
Get:3 http://us.archive.ubuntu.com/ubuntu zesty/main amd64 libfftw3-dev amd64 3.3.5-3 [2,123 kB]
Get:4 http://us.archive.ubuntu.com/ubuntu zesty/main amd64 libfftw3-doc all 3.3.5-3 [173 kB]
Fetched 2,877 kB in 1s (2,326 kB/s)
Selecting previously unselected package libfftw3-quad3:amd64.
(Reading database ... 423617 files and directories currently installed.)
Preparing to unpack .../libfftw3-quad3_3.3.5-3_amd64.deb ...
Unpacking libfftw3-quad3:amd64 (3.3.5-3) ...
Selecting previously unselected package libfftw3-bin.
Preparing to unpack .../libfftw3-bin_3.3.5-3_amd64.deb ...
Unpacking libfftw3-bin (3.3.5-3) ...
Selecting previously unselected package libfftw3-dev:amd64.
Preparing to unpack .../libfftw3-dev_3.3.5-3_amd64.deb ...
Unpacking libfftw3-dev:amd64 (3.3.5-3) ...
Selecting previously unselected package libfftw3-doc.
Preparing to unpack .../libfftw3-doc_3.3.5-3_all.deb ...
Unpacking libfftw3-doc (3.3.5-3) ...
dpkg: error processing archive /var/cache/apt/archives/libfftw3-doc_3.3.5-3_all.deb (--unpack):
 trying to overwrite '/usr/share/info/fftw3.info.gz', which is also in package imgcnv 1.66
Errors were encountered while processing:
 /var/cache/apt/archives/libfftw3-doc_3.3.5-3_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

ProblemType: Package
DistroRelease: Ubuntu 17.04
Package: libfftw3-doc (not installed)
ProcVersionSignature: Ubuntu 4.10.0-30.34-generic 4.10.17
Uname: Linux 4.10.0-30-generic x86_64
ApportVersion: 2.20.4-0ubuntu4.5
AptOrdering:
 libfftw3-quad3:amd64: Install
 libfftw3-bin:amd64: Install
 libfftw3-dev:amd64: Install
 libfftw3-doc:amd64: Install
 NULL: ConfigurePending
Architecture: amd64
Date: Sat Aug 5 16:57:23 2017
ErrorMessage: trying to overwrite '/usr/share/info/fftw3.info.gz', which is also in package imgcnv 1.66
InstallationDate: Installed on 2017-04-08 (119 days ago)
InstallationMedia:

RelatedPackageVersions:
 dpkg 1.18.10ubuntu2
 apt 1.4
SourcePackage: fftw3
Title: package libfftw3-doc (not installed) failed to install/upgrade: trying to overwrite '/usr/share/info/fftw3.info.gz', which is also in package imgcnv 1.66
UpgradeStatus: Upgraded to zesty on 2017-04-24 (103 days ago)

[dino99 (9d9)]

That version is now dead
http://news.softpedia.com/news/ubuntu-17-04-zesty-zapus-has-reached-end-of-life-upgrade-to-ubuntu-17-10-now-519360.shtml