trying to snapshot packrat returns error "Unable to retrieve package records for the following packages: - "file2c844fe4f20", "file8bc708d50e3""

Apologies, but I'm pretty confused by this one:

packrat::snapshot()
Error: Unable to retrieve package records for the following packages:
- "file2c844fe4f20", "file8bc708d50e3"

It's looking for packages that aren't packages?
I thought I'd check what it thought it needed:

packrat:::appDependencies()
 [1] "BH"         "R6"         "Rcpp"       "assertthat" "bindr"      "bindrcpp"   "cellranger" "cli"        "crayon"     "dplyr"     
[11] "fansi"      "glue"       "hms"        "magrittr"   "packrat"    "pillar"     "pkgconfig"  "plogr"      "purrr"      "qdapRegex" 
[21] "readr"      "readxl"     "rematch"    "rlang"      "stringi"    "stringr"    "tibble"     "tidyselect" "utf8"

No "file2..." there

not in packrat.lock either:

PackratFormat: 1.4
PackratVersion: 0.4.9.3
RVersion: 3.5.1
Repos: CRAN=https://cran.rstudio.com/

Package: Rcpp
Source: CRAN
Version: 0.12.19
Hash: fdff9c3aa69adac28cd5c45cd250c9da

Package: assertthat
Source: CRAN
Version: 0.2.0
Hash: e8805df54c65ac96d50235c44a82615c

Package: cellranger
Source: CRAN
Version: 1.1.0
Hash: 4e1ef4d099b0c5fd531a3938cf4624bd
Requires: rematch, tibble

Package: cli
Source: CRAN
Version: 1.0.1
Hash: a742a3229dbf7085c3a737af10e5065b
Requires: assertthat, crayon

Package: crayon
Source: CRAN
Version: 1.3.4
Hash: ff2840dd9b0d563fc80377a5a45510cd

Package: fansi
Source: CRAN
Version: 0.4.0
Hash: f147621f72b561485bfffcae78c4f5d5

Package: packrat
Source: CRAN
Version: 0.4.9-3
Hash: 03fb817297975f1da0d1b774b47620b3

Package: pillar
Source: CRAN
Version: 1.3.0
Hash: 3e43f774fa6dfba877caca1aebbeaa6a
Requires: cli, crayon, fansi, rlang, utf8

Package: readxl
Source: CRAN
Version: 1.1.0
Hash: db6da4b7012b3f8cf9cdc4d1c3758d50
Requires: Rcpp, cellranger, tibble

Package: rematch
Source: CRAN
Version: 1.0.1
Hash: ad4faf59e7611117ff165817074c50c7

Package: rlang
Source: CRAN
Version: 0.2.2
Hash: 49b735b7b1d14f561d21cce12c6703df

Package: tibble
Source: CRAN
Version: 1.4.2
Hash: 83895360ce4f8d2ce92eee00526b5b0b
Requires: cli, crayon, pillar, rlang

Package: utf8
Source: CRAN
Version: 1.1.4
Hash: f3f97ce59092abc8ed3fd098a59e236c

It's really quite a small project, no non-cran material, no custom packages, just a script and some helper functions

Reproduce the failure with packrat::snapshot() and inspect packrat:::appDependencies() alongside the shown packrat.lock. Trace where the file2c844fe4f20 and file8bc708d50e3 records are introduced, then verify that snapshot completes for this small CRAN-only project without reporting them as packages.