More specifically, the error seems related to an account that I've marked as "Sched D: Short/Long gain or loss" and a specific transaction in that account.  If I remove that account from tax options, or if I narrow the date range to exclude that one transaction, then I get no errors.

Any idea why one transaction would break the whole report?

Testing further back in time, I am finding that ANY transaction in any Capital Gains account is causing this error.  So now it doesn't look like any one thing I am doing specifically, but a problem with the capital gains component of this report.

I can reproduce this on MacOS. The Guile stack trace from gnucash.trace is:
* 13:17:53  WARN <gnc.scm> In ice-9/boot-9.scm:
2401: 19 [save-module-excursion #<procedure 10f0db810 at ice-9/eval-string.scm:65:9 ()>]
In ice-9/eval-string.scm:
  44: 18 [read-and-eval #<input: string 11313b9c0> #:lang ...]
  37: 17 [lp (gnc:report-run 0)]
In report.scm:
 816: 16 [gnc:report-run 0]
In c-interface.scm:
  70: 15 [gnc:backtrace-if-exception #<procedure 10f0dfd80 at report.scm:817:5 ()>]
  22: 14 [gnc:call-with-error-handling #<procedure 10f0dfd80 at report.scm:817:5 ()> ...]
In ice-9/boot-9.scm:
 157: 13 [catch #t #<procedure 10f0dfd50 at c-interface.scm:23:8 ()> ...]
In c-interface.scm:
  27: 12 [#<procedure 10f0dfd50 at c-interface.scm:23:8 ()>]
In report.scm:
 820: 11 [#<procedure 10f0dfd80 at report.scm:817:5 ()>]
 791: 10 [gnc:report-render-html # #t]
In taxtxf.scm:
3268: 9 [generate-tax-schedule "Taxable Income/Deductible Expenses" ...]
In srfi/srfi-1.scm:
 576: 8 [map #<procedure 10f513760 at taxtxf.scm:3268:22 (form-line-acct)> (# #)]
In taxtxf.scm:
2896: 7 [handle-tax-code (# # # # ...)]
2304: 6 [handle-account # # #t ...]
1342: 5 [process-account-transaction-detail # # # ...]
In srfi/srfi-1.scm:
 578: 4 [map #<procedure 10fcdaa50 at taxtxf.scm:1342:13 (split)> (# # # # ...)]
In taxtxf.scm:
1449: 3 [#<procedure 10fcdaa50 at taxtxf.scm:1342:13 (split)> #]
 887: 2 [process-transaction-multi-transfer-detail # # # ...]
In srfi/srfi-1.scm:
 578: 1 [map #<procedure 11313b5b0 at taxtxf.scm:887:13 (tran-split)> (# # # #)]
In taxtxf.scm:
 976: 0 [#<procedure 11313b5b0 at taxtxf.scm:887:13 (tran-split)> #]

ERROR: In procedure car: Wrong type argument in position 1 (expecting pair): 1504177140

I believe this was missed out during TP->T64... try changing the "(car trans-date)" in line 976 to "trans-date" and I think it should fix it.

This problem has been fixed in our software repository. The fix will go into the next software release. Once that release is available, you may want to check for a software upgrade provided by your Linux distribution.

GnuCash bug tracking has moved to a new Bugzilla host. This bug has been copied to https://bugs.gnucash.org/show_bug.cgi?id=796081. Please update any external references or bookmarks.